Biophysical Blog

Biomarker Glossary

ADENOVIRUS ANTIBODY


This is an antibody against a virus called an adenovirus, which is a frequent cause of the common cold. The presence of this antibody indicates recent infection. Adenoviruses most commonly cause respiratory illness; however, depending on the infecting serotype (more than 50 types are known to infect humans), they may also cause gastroenteritis, conjunctivitis, hemorrhagic cystitis, and other illnesses. Symptoms of respiratory illness caused by adenovirus infection range from the common cold syndrome to pneumonia, croup, and bronchitis. Patients with compromised immune systems are especially susceptible to severe complications of adenovirus infection. Acute respiratory disease (ARD), first recognized among military recruits during World War II, can be caused by adenovirus infections during conditions of crowding and stress.

ADIPONECTIN


Adiponectin is a hormone produced by fat cells that regulates the metabolism of lipids and glucose. Low levels of this hormone are found in people who are obese or who are at increased risk of heart attack. Adiponectin is produced and secreted exclusively by adipocytes, which regulate the metabolism of lipids and glucose. This hormone influences the body’s response to insulin and has anti-inflammatory effects on vascular endothelial cells. High blood levels are associated with a reduced risk of heart attack.

ALANINE AMINOTRANSFERASE(ALT, ALSO CALLED SGPT)


Alanine aminotransferase (ALT) is an enzyme found predominantly in liver and heart cells. Its level may be abnormally high in conditions that cause liver damage or after a heart attack. Blood levels of alanine aminotransferase (ALT) are normally low; however, liver damage (for example, due to viral hepatitis) releases ALT into the bloodstream, causing levels to rise. The ALT test is often done to determine liver function in conjunction with other tests, including aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin. Serum ALT levels are also increased after myocardial infarction or as a result of some medications. ALT is also called serum glutamic pyruvic transaminase (SGPT).

ALBUMIN


Albumin is a protein manufactured by the liver and found in abundance in the bloodstream. Its level can be abnormal in a variety of diseases and malnutrition conditions. Albumin is the most abundant protein in plasma and transports many small molecules, including bilirubin, calcium, progesterone, and certain drugs. It is also of prime importance in maintaining the oncotic pressure of the blood, since its concentration in blood is much greater than it is in extracellular fluid. Because albumin is synthesized by the liver, decreased serum albumin may result from liver disease. It can also result from kidney disease, which allows albumin to escape into the urine, or be caused by malnutrition or a low-protein diet.

ALBUMIN/GLOBULIN RATIO


The ratio of albumin to globulin in the blood may be abnormal in certain blood and immune system conditions as well as some liver and kidney diseases. A low albumin/globulin ratio may be due to overproduction of gamma globulin (as seen in monoclonal/polyclonal gammopathy, multiple myeloma or autoimmune diseases) or low levels of albumin (due to low production, as in cirrhosis, or excessive loss, as in nephrotic syndrome or protein-losing enteropathy). A high ratio suggests disorders involving low gamma-globulin production, such as agammaglobulinemia.

ALKALINE PHOSPHATASE(ALP)


Alkaline phosphatase (ALP) is an enzyme found in many tissues, including liver, bile duct, placenta, and bone. Its level may be elevated in conditions that damage or disrupt the liver, bile ducts, or bone. Because damaged or diseased tissue releases enzymes into the blood, serum ALP levels can be abnormal in many conditions, including bone disease and liver disease. Serum ALP is also increased in some normal circumstances (for example, during normal bone growth or bone fracture) or in response to a variety of drugs.

ALPHA-1-ANTITRYPSIN(A1AT)


Alpha-1-antitrypsin (A1AT) is a protein made in the liver that protects the lungs so they can work normally. Alpha-1-antitrypsin is the major protease (trypsin, chymotrypsin, elastase) inhibitor in human serum. An inherited deficiency is associated with liver and lung disease. Low levels can also be found in neonatal respiratory distress syndrome and severe protein-losing disorders. In some adults, alpha-1-antitrypsin deficiency is complicated by cirrhosis, liver cancer, rheumatoid arthritis, and pancreatitis. Increased levels may be associated with inflammation.

ALPHA-2-MACROGLOBULIN(A2M)


Alpha-2-macroglobulin (A2M) is a major blood protein that may be abnormal in certain liver, kidney, and pancreas conditions. Alpha-2-macroglobulin (A2M) function ranges from ion transport to inhibition of proteinases. Elevated levels are seen in conditions such as cirrhosis, nephrotic syndrome, severe burns, and diabetes. Decreased levels are seen in pancreatitis, fibrinolysis, and liver disease. A rare A2M deletion polymorphism has been linked to an increased risk of Alzheimer’s disease, although the mechanism is unknown.

ALPHA-FETOPROTEIN(AFP)


Alpha-fetoprotein (AFP) is a fetal protein that is detected in the mother’s blood during pregnancy. Although not diagnostic of any specific disease, it can be used as a tumor marker when found in non-pregnant adults. Its concentration peaks in the fetal bloodstream at 2-3 g/l around 12-14 weeks of gestation and then falls. Fetal malformations such as neural tube defects elevate maternal serum levels. Normal values in adult males and non-pregnant females are very low (< 40 micrograms/liter). Among cancer patients, elevated levels are seen most frequently in adults with germ cell tumors or hepatocellular carcinoma but also occur in gastric, testicular, colon, biliary, pancreatic, and lung cancers.

AMYLASE


Amylase is a digestive enzyme produced in the salivary glands and pancreas. Its levels may be elevated if the pancreas is inflamed or damaged. Amylase is involved in the digestion of glycogen and starch. Pancreatic disease or inflammation can cause amylase to escape into the blood. Drugs that can increase amylase levels include asparaginase, aspirin, cholinergic agents, corticosteroids, indomethacin, loop and thiazide diuretics, methyldopa, opiates (such as codeine and morphine), oral contraceptives, and pentazocine.

ANDROSTENEDIONE


Androstenedione is a natural steroid hormone that is modified within the body to produce the male sex hormone testosterone and the female sex hormone estrogen. Taken orally, androstenedione will increase blood levels of testosterone. Levels of this hormone may be abnormal in certain glandular conditions. Androstenedione is a 19-carbon steroid hormone and is a direct precursor to the androgen testosterone and the estrogens estrone and estradiol. Some androstenedione is secreted into the plasma and may be converted to testosterone in peripheral tissues. Androstenedione production is governed by the adrenocorticotropic hormone (ACTH).

ANTI-NUCLEAR ANTIBODY(ANA)


Anti-nuclear antibodies (ANA) are antibodies that can bind to certain structures within the nucleus of our cells. Normally, there are no ANAs in the blood, but they may be detected in a variety of autoimmune diseases and arthritis conditions or even in some people who don’t have any specific disease. ANAs are gamma-globulins helpful in the evaluation of systemic lupus erythematosus (SLE) and drug-induced lupus, but levels may also be positive in cases of scleroderma, Sjögren’s syndrome, Raynaud’s disease, juvenile chronic arthritis, rheumatoid arthritis, antiphospholipid antibody syndrome, autoimmune hepatitis, type 1 diabetes mellitus, and many other autoimmune and non- rheumatological conditions associated with tissue damage. Due to the many potential causes of a positive result, additional testing is often needed.

ANTI-SACCHAROMYCES CEREVISIAE ANTIBODY(ASCA)


Anti-Saccharomyces cerevisiae (ASCA) testing may be useful in the evaluation of suspected inflammatory bowel disease, including Crohn’s disease and ulcerative colitis. Anti-Saccharomyces cerevisiae mannan antibodies have been proposed as a new serological marker associated with Crohn’s disease. However, their clinical value is still unclear.

APOLIPOPROTEIN AI(Apo AI)


An apolipoprotein is the protein constituent of a lipoprotein, a large molecule that transports triglycerides and cholesterol through the blood. Apolipoprotein AI (Apo AI) is found in high-density lipoprotein (HDL) particles, which transport the cholesterol known as “good cholesterol.” Apo AI is instrumental in promoting the transfer of cholesterol into the liver, where it is metabolized and then excreted from the body via the intestines. Very low levels of Apo AI may be associated with a higher risk of coronary heart disease. Apo AI serves to prevent the accumulation of cholesterol-loaded macrophages, which deposit on arterial walls as foam cells (a prominent early feature of atherosclerotic lesion formation). Its primary function is to activate lecithin-cholesterol acyltransferase (LCAT) within the HDL complex, which catalyzes the esterification of cholesterol. This results in a more soluble cholesterol-HDL complex, increasing the cholesterol transport capacity of the HDL particle for subsequent removal by the liver. Apo AI is therefore a convenient marker for assessing the cholesterol-clearing capacity of the blood, and studies have clearly indicated that it is a better discriminator of angiographically documented coronary artery disease than is HDL cholesterol.

APOLIPOPROTEIN CIII(Apo CIII)


An apolipoprotein is the protein constituent of a lipoprotein, a large molecule that transports triglycerides and cholesterol through the blood. Apolipoprotein CIII (Apo CIII) is made in the liver and is found in very-low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) particles. Very low levels of Apo CIII may be associated with a higher risk of coronary heart disease. Synthesized predominantly in the liver and to a lesser degree in the intestine, Apo CIII is found in VLDL, HDL, and chylomicron remnants, and elevated levels are associated with both primary and secondary hypertriglyceridemia. It is a cofactor for sphingomyelinase, an inhibitor of lipoprotein lipase (LPL), and may activate lecithin-cholesterol acyltransferase (LCAT). Apo CIII has been recognized as an emerging risk marker that may play a role in more effective coronary artery disease (CAD) risk assessment.

APOLIPOPROTEIN H(Apo H)


An apolipoprotein is the protein constituent of a lipoprotein, a large molecule that transports triglycerides and cholesterol through the blood. Apolipoprotein H (Apo H) is a lipoprotein made primarily by the placenta. Levels of this protein may be abnormal when miscarriages occur. The human Apo H molecule, also known as beta-2-glycoprotein 1, is expressed by placental trophoblast cells at high levels. Although its normal physiological role is not known, it appears to act as a cofactor for the binding of phospholipid autoantibodies to trophoblasts, a process involved in the pathogenesis of recurrent miscarriage (antiphospholipid syndrome). Genetic variation in apolipoprotein H affects the occurrence of antiphospholipid antibodies and apolipoprotein H concentrations in systemic lupus erythematosus.

ASPARTATE AMINOTRANSFERASE(AST, ALSO CALLED SGOT)


Aspartate aminotransferase (AST, also called SGOT) is an enzyme found in liver, muscle, and heart tissues. Diseases that affect liver cells cause them to release AST, and AST levels are also increased after a heart attack. However, mild to moderate elevations of AST are not uncommon in otherwise healthy individuals. In viral hepatitis and other forms of liver disease associated with hepatic necrosis, levels of serum AST and ALT (alanine aminotransferase) are elevated even before clinical signs and symptoms appear. Although 20- to 50-fold elevations are more frequently encountered, both enzymes may reach values as high as 100 times the upper limit of normal (ULN). Serum AST levels also increase after myocardial infarction. Pulmonary emboli can raise AST levels to 2 to 3 times the ULN, and slight to moderate elevations (2 to 5 times the ULN) are seen in acute pancreatitis, crushed muscle injuries, gangrene, and hemolytic disease.

ASPARTATE AMINOTRANSFERASE ANTIGEN(AST Ag, ALSO CALLED SGOT ANTIGEN)


Aspartate aminotransferase antigen (AST Ag, also called SGOT antigen) is an enzyme present in liver and muscle cells. Its levels are elevated in conditions affecting the heart and liver, such as viral hepatitis, hepatic congestion, myocarditis, and myocardial infarction.

B-TYPE NATRIURETIC PEPTIDE(BNP)


B-type natriuretic peptide (BNP) is found only in the ventricles of the heart. Elevation may indicate congestive heart failure. There is strong correlation between the degree of decompensation of congestive heart failure and the level of B-type natriuretic peptide. In addition, it has been very helpful in the differential diagnosis of the patient presenting with dyspnea. Recent studies suggest that B-type natriuretic peptide may have important prognostic significance in patients presenting with an acute coronary syndrome.

BASOPHIL COUNT


A basophil is a type of white blood cell that is involved in the body’s response to infections and allergic stimuli. Basophil levels may be elevated in conditions involving inflammation and allergic reactions. Basophils are granular leukocytes with an irregularly shaped, pale-staining nucleus that is partially constricted into two lobes. Their cytoplasm contains coarse, bluish-black granules that contain histamines, heparin, and serotonin, which are released on appropriate stimulation. An increased serum level of basophils is often seen in myxedema, hypothyroid conditions, ulcerative colitis, certain types of anemia, and in response to parasitic infections and allergic stimuli. An alteration in bone marrow function, such as leukemia or Hodgkin’s disease, may also cause an increase in basophil numbers, while corticosteroid drugs, allergic reactions, and acute infections may cause already-low basophil numbers to decrease.

BASOPHIL PERCENTAGE


The percentage of basophils (a type of white blood cell involved in the body’s response to infections and allergic stimuli) out of all the white blood cells is helpful in diagnosing certain diseases. Basophils are granular leukocytes with an irregularly shaped, pale-staining nucleus that is partially constricted into two lobes. Their cytoplasm contains coarse, bluish-black granules that contain histamines, heparin, and serotonin, which are released on appropriate stimulation. An increased serum level of basophils is often seen in myxedema, hypothyroid conditions, ulcerative colitis, certain types of anemia, and in response to parasitic infections and allergic stimuli. An alteration in bone marrow function, such as leukemia or Hodgkin’s disease, may also cause an increase in basophil numbers, while corticosteroid drugs, allergic reactions, and acute infections may cause already-low basophil numbers to decrease.

BETA-2-GLYCOPROTEIN ANTIBODY(B2GP Ab)


Antibodies to beta-2-glycoprotein (B2GP Ab) are found in conditions such as antiphospholipid syndrome, a clotting disorder which can cause recurrent miscarriage. Beta-2-glyocoprotein antibodies are also associated with an increased risk of venous and arterial thrombosis and thrombocytopenia. Unlike cardiolipin autoantibodies, which can be transiently found after infectious disease, beta-2-glycoprotein antibodies are found only in patients with autoimmune diseases.

BETA-2-MICROGLOBULIN(B2M)


Beta-2-microglobulin (B2M) is a protein found on the surface of most cells. Its levels may be especially elevated in kidney failure, inflammation, and certain cancers. B2M is found on the surfaces of all nucleated cells and is shed into the blood, particularly by tumor cells and lymphocytes. Due to its small size, it passes through the kidney’s glomerular membrane, but normally less than 1% is excreted due to reabsorption in the proximal tubules. Therefore, high plasma levels occur in renal failure, inflammation, and neoplasms, especially those associated with B-lymphocytes, and the plasma level is particularly useful in monitoring kidney transplant recipients. Beta-2-microglobulin concentrations are sometimes increased in cerebrospinal fluid (relative to serum) in acute lymphoblastic leukemia (ALL), lymphoma, and lymphoproliferative diseases.

BILIRUBIN, TOTAL


Bilirubin is a yellow breakdown product of hemoglobin, the oxygen-carrying molecule in red blood cells (RBCs). Bilirubin levels may be elevated in patients with liver disease or a blocked bile duct. Bilirubin is produced by catabolism of the heme molecule from erythrocytes. Approximately 85% come from senescent RBCs that are destroyed in the liver, spleen, and bone marrow, while the remainder comes from RBC precursors destroyed in the bone marrow and the catabolism of other heme-containing proteins, such as myoglobin, cytochromes, and peroxidases. In the hepatocytes, bilirubin is rapidly conjugated with glucuronic acid to produce bilirubin monoglucuronide (10%) and diglucuronide (90%), which are then excreted into bile. The total bilirubin value includes both conjugated and unconjugated bilirubin, whereas bilirubin fractionation distinguishes between the levels of each. High unconjugated bilirubin levels are most commonly seen in newborns due to premature breakdown of erythrocytes and ineffective erythropoiesis, although Crigler-Najjar syndrome and Gilbert’s syndrome also produce unconjugated bilirubinemia through the inability to conjugate bilirubin at the normal rate. Conjugated bilirubin levels increase to abnormal values when any portion of the biliary tree becomes blocked or abnormally permeable, retarding the passage of bilirubin and other bile components.

BLOOD UREA NITROGEN(BUN)


Blood urea nitrogen (BUN) is a test that measures the amount of urea nitrogen in the blood. Urea is the major breakdown product of bodily protein and contains nitrogen. Urea and other nitrogen-rich waste products are normally eliminated from the bloodstream by the kidneys, so an increased BUN level may indicate impaired renal (kidney) function. However, many factors besides renal disease can cause BUN alterations. An elevated BUN level may also be caused by congestive heart failure as a result of poor renal perfusion, dehydration, shock, hemorrhage into the gastrointestinal tract, acute myocardial infarction, stress, or excessive protein intake or protein catabolism. A decreased level may be seen in liver failure, malnutrition, anabolic steroid use, or impaired nutrient absorption. In patients with liver disease, the BUN level may be low even if the kidneys are normal.

BLOOD UREA NITROGEN/CREATININE RATIO


Unlike urea, blood creatinine is relatively insensitive to body hydration and the presence of blood or meat in the intestinal tract; therefore, the blood urea nitrogen (BUN)-to-creatinine ratio may help to distinguish impaired kidney function due to dehydration from other kinds of kidney damage. The ratio of BUN:creatinine is normally 10:1 but can increase to 20:1 or even higher with dehydration. An increased BUN:creatinine ratio may also be due to certain types of kidney disease, breakdown of blood in the intestinal tract, increased dietary protein, or any clinical circumstance resulting in reduced blood flow to the kidneys (such as heart failure or renal artery disease). The BUN:creatinine ratio is decreased in other renal conditions, liver disease, malnutrition, and sickle cell anemia.

BORDETELLA PERTUSSIS ANTIBODY(B. PERTUSSIS Ab)


Bordetella pertussis antibody is evidence of recent infection with, exposure to, or vaccination with Bordetella pertussis, the bacterium causing whooping cough.

BRAIN-DERIVED NEUROTROPHIC FACTOR(BDNF)


Brain-derived neurotrophic factor (BDNF) is a protein found in the central nervous system, which is important to the survival of existing brain cells and the growth of new brain cells. BDNF levels may be abnormally low in certain nervous system conditions such as depression and Alzheimer’s disease. Neurotrophins are soluble polypeptide growth factors widely recognized for their roles in the mammalian nervous system. BDNF is a central nervous system protein that helps to support existing neurons and encourage neural and synaptic growth. Mice born without the ability to make BDNF suffer developmental defects in the brain and sensory nervous system and usually die soon after birth, suggesting that BDNF plays an important role in normal development. Exposure to stress and the stress hormone corticosterone decreases the expression of BDNF in rats and leads to eventual atrophy of the hippocampus if exposure is persistent. Similar atrophy has been shown to take place in humans suffering from long-term depression, while physical activity has been reported to increase BDNF expression in the brain and spinal cord. Various studies have shown possible links between low BDNF levels and other affective disorders.

C-PEPTIDE


C-peptide (also called insulin C-peptide) is a subunit of the hormone insulin. C-peptide is measured in newly diagnosed diabetes patients to determine how much insulin is being produced in the body. Insulin is formed by the cleavage of C-peptide from proinsulin, and C-peptide is released from the pancreas in equimolar concentrations with insulin. However, it has no known biologic activity. C-peptide is measured to evaluate residual beta cell function in patients with insulin-treated diabetes mellitus in order to distinguish endogenous from exogenous insulin sources. In transient diabetes mellitus, the return of C-peptide concentrations to within the normal range provides evidence of remission.

C-REACTIVE PROTEIN(CRP)


C-reactive protein (CRP) is a protein produced in the liver, whose levels rise dramatically in the presence of inflammation or infection. Although not a telltale diagnostic sign of any one condition, CRP may be measured to check for rheumatoid arthritis or to measure a patient’s response to treatment. As a marker of inflammation, CRP has also been established as an important predictor of cardiovascular risk. As an acute phase reactant, CRP can be used as a general screening aid for inflammatory diseases, infections, and neoplasms. In addition, CRP in large concentrations (>5 mg/dL) predicts progression of erosions in rheumatoid arthritis. Elevated serum CRP is characteristic of bacterial, but not viral, meningitis or meningoencephalitis. Elevated CRP levels are also associated with an increased risk of myocardial infarction in patients with stable and unstable angina and predict the risk of first myocardial infarction and ischemic stroke in apparently healthy individuals.

CALCITONIN


Calcitonin is a hormone secreted by the thyroid. It helps to regulate calcium and phosphate levels in the bloodstream and promotes bone formation. Calcitonin levels may be significantly elevated in thyroid cancer. Calcitonin is secreted by the parafollicular C-cells of the thyroid. Its primary physiological effect is to lower serum calcium and phosphate levels. Elevated levels of calcitonin (>100 pg/ml) may be encountered in a variety of pathological conditions, including leukemias and myeloproliferative disorders. The test is most often used to detect and confirm medullary carcinoma of the thyroid gland, and calcitonin may be detectable in blood even when the tumor is clinically occult. It is also used as a serum tumor marker for small cell (oat cell) lung carcinoma.

CALCIUM(Ca)


Calcium (Ca) is an element found in the body that is an important component of bone. It is also important in normal cell function, muscle contraction, heart action, nervous system maintenance, and blood clotting. The parathyroid glands regulate serum calcium concentrations and bone metabolism. In turn, serum calcium concentrations regulate parathyroid hormone (PTH) secretion via negative feedback. Hypercalcemia may be caused by hyperparathyroidism, multiple myeloma, or excessive vitamin D intake, while hypocalcemia may result from hypoparathyroidism, low vitamin D intake, pregnancy, osteomalacia, and certain renal diseases.

CAMPYLOBACTER JEJUNI ANTIBODY(C. JEJUNI Ab)


Campylobacter jejuni is a bacterium that causes infectious diarrhea. The antibody against C. jejuni indicates recent infection with or prior exposure to these bacteria. C. jejuni infection causes cramping, diarrhea, abdominal pain, and fever within 2 to 5 days after exposure to the organism. It is one of the most common bacterial causes of diarrhea. Most cases come from handling or ingesting raw or undercooked poultry.

CANCER ANTIGEN 15-3(BR-MA)


BR-MA, also called cancer antigen 15-3 (CA-15-3), is a tumor marker most useful as an indicator of the effects of treatment in women diagnosed with breast cancer, especially advanced breast cancer. Other conditions that may also raise BR-MA levels include lung cancer, ovarian cancer, prostate cancer, benign breast or ovarian disease, endometriosis, pelvic inflammatory disease, hepatitis, pregnancy, and lactation. BR-MA measures a circulating adenocarcinoma-associated antigen belonging to a family of high molecular- weight glycoproteins normally present in human milk fat globule membranes. Although elevated levels are present in only a small percentage of patients with localized disease, two-thirds of cases with metastasis will have significantly elevated levels. BR-MA levels may also be elevated in patients with cirrhosis, sarcoidosis, tuberculosis, systemic lupus erythematosus, and malignancies of the pancreas, colon, and liver.

CANCER ANTIGEN 19-9(CA 19-9)


Cancer antigen 19-9 (CA 19-9) is a cancer marker whose levels may be elevated in cancers of the digestive tract (colorectal, pancreatic, stomach, and bile duct cancers), particularly cancer of the pancreas. Higher levels of CA 19-9 tend to be associated with more advanced disease, but several noncancerous conditions may also elevate CA 19-9 levels, including gallstones, pancreatitis, and cirrhosis of the liver. CA 19-9 is a derivative of the Leab blood group antigen present on normal mesenteric epithelium and thus is not expressed in Lewis-negative individuals (about 7% of the U.S. population). One use of CA 19-9 is in predicting the operability of carcinoma of the pancreas. It is also expressed in most patients with carcinomas of the liver, biliary tract, stomach, and colon. The specificity of CA 19-9 is limited by its expression in patients with pancreatitis and inflammatory gastrointestinal diseases. CA 19-9 and carcinoembryonic antigen (CEA) may be used together to help differentiate benign disease from pancreatic carcinoma, since elevations of both are suggestive of neoplasia.

CANCER ANTIGEN 125(CA 125)


This test may be used to follow women who have already been diagnosed with ovarian cancer and is a good indicator of whether a patient is responding to treatment and whether she remains in remission after treatment. Cancer antigen 125 (CA 125) is a glycoprotein found in increased amounts on the cell surfaces of many ovarian epithelial malignancies. Elevated CA 125 levels are associated with serous, endometrioid, and clear cell carcinomas of the ovary. More than 80% of non-mucinous, epithelial ovarian carcinomas, as well as many uterine tumors, express elevated levels of CA 125. However, conditions such as endometriosis, normal pregnancy, pelvic inflammatory disease, uterine fibroids, hepatitis, pancreatitis, and cirrhosis may also contribute to elevated serum CA 125 levels. Breast, lung, and gastrointestinal tract cancers may also be associated with an elevation of this tumor marker.

CARBON DIOXIDE(CO2)


Carbon dioxide (CO2) is a gas that dissolves in water to make carbonic acid, which means that measurement of carbon dioxide levels in the blood can help to indicate the blood’s acidity. Measurement of CO2 content is part of an electrolyte panel to screen for an electrolyte or acid-base imbalance. Higher than normal carbon dioxide levels may reflect excessive loss of acid (as with recurrent vomiting or continuous gastric drainage) or acid-base disorders (such as primary aldosteronism or Cushing syndrome). Lower than normal levels are common in acidosis (as in diabetic ketoacidosis, kidney disease, and severe diarrhea) or respiratory alkalosis.

CARCINOEMBRYONIC ANTIGEN(CEA)


Carcinoembryonic antigen (CEA) is a protein normally found in fetal gut tissue. Its levels may be increased in the presence of various cancers, particularly colon and rectal cancer, but also breast, lung, pancreatic, thyroid, and genitourinary cancers. Benign conditions, including smoking, infection, inflammatory bowel disease, and liver disease, can also raise CEA levels. Carcinoembryonic antigen levels are used to monitor patients with various malignancies, evaluate response to therapy, and potentially indicate recurrence and prognosis. CEA has broad tumor specificity; elevated levels are seen in cancers of the colon, rectum, stomach, breast, lung, pancreas, thyroid, and genitourinary system. Higher levels also may indicate a greater likelihood of metastasis. Levels usually fall following successful treatment and remain stable; rising levels in these patients may indicate recurrence.

CENTROMERE PROTEIN B ANTIBODY(CENP-B Ab)


Antibodies to centromere protein B are found in a variety of autoimmune conditions and arthritis diseases. Centromere antibodies demonstrate a specific anti-nuclear antibody assay pattern, which is present in 80% to 90% of individuals with CREST variant scleroderma, 30% of Raynaud’s syndrome patients, 12% of patients with mixed connective-tissue disease, diffuse scleroderma, interstitial pulmonary fibrosis, or primary biliary cirrhosis, and a smaller percentage of patients with systemic lupus erythematosus and rheumatoid arthritis.

CHLAMYDIA PNEUMONIAE ANTIBODY(C. PNEAUMONIAE Ab)


Chlamydia pneumoniae is a bacterium that causes pneumonia, bronchitis, sinusitis and pharyngitis in both adults and children. Chronic low-level infection may injure blood vessels and has been seen in patients who have suffered a heart attack or heart disease. The presence of this antibody indicates recent infection with or exposure to C. pneumoniae. In addition to causing pneumonia and other upper and lower respiratory ailments, chronic infection with C. pneumoniae can initiate and perpetuate vascular endothelial damage and has recently been implicated in atherogenesis, asthma, otitis media, multiple sclerosis, and age-related macular degeneration. Studies have demonstrated a consistent association between elevated C. pneumoniae antibody titers and myocardial infarction or chronic heart disease.

CHLAMYDIA TRACHOMATIS ANTIBODY(C. TRACHOMATIS Ab)


Chlamydia trachomatis is a bacterium that is transmitted by sexual contact and commonly causes infections of the female reproductive tract. This antibody indicates recent infection with or exposure to C. trachomatis. It is one of the most common sexually transmitted organisms in the U.S. today, with more than 3 million people infected each year. It is asymptomatic in 80% of women and 50% of men but may result in cervicitis or pelvic inflammatory disease in females, urethritis or epididymitis in males, and conjunctivitis or pneumonia in neonates.

CHLORIDE(Cl)


Chloride (Cl) is an electrolyte that is important in water distribution and general cell function. Its levels may be abnormal in a variety of metabolic and kidney conditions. Chloride is significantly involved in the maintenance of water distribution, osmotic pressure, blood pH, kidney function, and acid-base balance. Hypochloremia is observed with burns, Cushing’s syndrome, heart failure, salt-losing nephritis, metabolic alkalosis, chronic compensated respiratory acidosis, and diabetic ketoacidosis. In Addison’s disease, chloride levels are usually maintained close to normal except in an Addisonian crisis, when chloride as well as sodium levels may drop significantly. Hyperchloremia occurs with dehydration, renal tubular acidosis, acute renal failure, metabolic acidosis associated with prolonged diarrhea and loss of sodium bicarbonate, diabetes insipidus, adrenocortical hyperfunction, hyperparathyroidism, salicylate intoxication, and respiratory alkalosis. Urinary excretion of chloride decreases when losses by other routes are increased.

CHOLESTEROL


Cholesterol is a lipid that is found in our diet as well as manufactured by the liver. It is an important component in a variety of hormones. Significant elevation in cholesterol levels is a risk factor for coronary heart disease. Although a portion of the body’s cholesterol is derived from dietary intake, most is synthesized by the liver and other tissues. A single total cholesterol value more than 20% below the suggested age- and sex-adjusted upper reference limits virtually eliminates a diagnosis of hyperlipoproteinemia. Total cholesterol, HDL-cholesterol, and LDL-cholesterol levels are highly useful in the determination of risk for coronary artery disease and stroke. Standardized by reference methods provided by the CDC, laboratory reference intervals reflect “ideal” or “healthy” levels for reduced risk with values relatively comparable from laboratory to laboratory.

COLLAGEN TYPE 1 ANTIBODY


Collagen autoantibodies have been observed in a variety of autoimmune diseases, including mixed connective tissue disease, systemic lupus erythematosus (SLE), progressive systemic sclerosis, rheumatoid arthritis (RA), and vasculitis. Collagen type 1 antibodies are found in about 85% of SLE patients, as well as in adult and juvenile RA and relapsing polychondritis.

COLLAGEN TYPE 2 ANTIBODY


Collagen autoantibodies have been observed in a variety of autoimmune diseases, including mixed connective tissue disease, systemic lupus erythematosus, progressive systemic sclerosis, rheumatoid arthritis (RA), and vasculitis. Collagen type 2 antibodies are present in the serum of about 70% of RA patients and 40% to 50% of relapsing polychondritis patients. Autoimmunity to type 2 collagen may be instrumental in the pathogenesis of RA.

COLLAGEN TYPE 4 ANTIBODY


Collagen autoantibodies have been observed in a variety of autoimmune diseases, including mixed connective tissue disease, systemic lupus erythematosus (SLE), progressive systemic sclerosis, rheumatoid arthritis, and vasculitis. Collagen type 4 antibodies occur in Goodpasture’s syndrome, scleroderma, SLE, progressive systemic sclerosis, polyarteritis nodosa, primary Raynaud’s phenomenon, and vasculitides, among other conditions.

COLLAGEN TYPE 6 ANTIBODY


Collagen autoantibodies have been observed in a variety of autoimmune diseases, including mixed connective tissue disease, systemic lupus erythematosus (SLE), progressive systemic sclerosis, rheumatoid arthritis, and vasculitis. Antibodies against collagen type 6 are present in a number of chronic diseases including diabetes mellitus, rheumatoid arthritis, and alcoholism.

COMPLEMENT 3(C3)


Complement 3 (C3) levels may be low in a variety of autoimmune diseases and other conditions. Quantitation of C3 is used to detect individuals with hereditary C3 deficiency or those with diseases in which complement is consumed at an increased rate. These include systemic lupus erythematosus, chronic active hepatitis, infective endocarditis, certain fungal and parasitic infections, septicemia, shock, and glomerulonephritis. Low C3 levels may also be seen in patients with burns, malignant hypertension, and disseminated intravascular coagulation. Elevated C3 levels may occur in cancer and ulcerative colitis.

COMPLEMENT FACTOR C1Q ANTIBODY(C1Q ANTIBODY)


Complement factor C1q is a protein involved in the immune system. Antibodies to C1q may be present in certain autoimmune diseases and arthritis conditions. C1q is a component of the C1 molecular complex, and C1q antibody levels are useful in the detection of circulating immune complexes (CICs). CICs are formed by the interaction of antibodies with specific antigens and are normally cleared rapidly by the reticuloendothelial system. However, in some cases, CICs are deposited in tissues with associated inflammatory- mediated damage. Elevated CIC levels have been detected in a variety of autoimmune diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis), certain cases of glomerulonephritis, infectious diseases (e.g., Lyme disease, chronic HBV infection, HIV infection, endocarditis), and some malignancies.

CORTISOL


Cortisol is an important steroid hormone that regulates numerous body systems, including the response to infection and inflammation, blood sugar levels, and bone metabolism. Cortisol levels are often measured to evaluate the function of the pituitary and adrenal glands. Cortisol (hydrocortisone) is primarily produced in the adrenal gland. It stimulates conversion of proteins to carbohydrates, raises blood glucose levels, and promotes glycogen storage in the liver. Cortisol levels may be elevated in patients with adrenal tumors and Cushing’s syndrome. Lower than normal levels may indicate Addison’s disease or hypopituitarism.

CREATINE


Creatinine is a protein waste product generated by muscle metabolism and eliminated by the kidneys. Creatinine is a useful indicator of kidney function, and its levels are significantly elevated when kidney function is impaired. Because creatinine is released at a constant rate (depending on muscle mass), its serum level is a good indicator of glomerular filtration rate and renal function. Daily excretion of creatinine can be increased by 10% to 30% as a result of dietary intake. Elevated levels may indicate diabetic nephropathy, preeclampsia or eclampsia, glomerulonephritis, or rhabdomyolysis. Lower than normal levels may indicate late stage muscular dystrophy or myasthenia gravis.

CREATINE KINASE MB(CK-MB)


Creatine kinase MB (CK-MB) is a protein derived from heart muscle. Levels of this protein are significantly elevated when the heart muscle is damaged, as occurs during a heart attack. Damaged cardiac tissue releases CK-MB from 2 to 8 hours following acute myocardial infarction (AMI). CK-MB values peak at 9 to 30 hours after infarction and return to baseline within 48 to 72 hours. They are also useful in monitoring reperfusion during thrombolytic therapy after AMI. Rhabdomyolysis and other causes of skeletal muscle injury can also increase CK-MB levels.

CREATINE KINASE, TOTAL(CK TOTAL)


Creatine kinase (CK) is an enzyme found in skeletal muscle, heart muscle, and brain tissue. Its levels are significantly elevated when skeletal or heart muscles are damaged. Its measurement is often used to diagnose a heart attack or evaluate an episode of chest pain. Also called CPK, CK is an enzyme catalyzing the reversible transfer of phosphate from phosphocreatine to ADP, forming creatine and ATP, which is of importance in muscle contraction. CK levels are elevated after myocardial infarction and in the presence of neuromuscular disease or muscle damage caused by drugs, trauma, or immobility.

CYTOCHROME P450 ANTIBODY


This antibody against one of the cytochrome P450 enzymes (a family of enzymes involved in the metabolism of foreign compounds) is sometimes present in patients with type II autoimmune hepatitis and other liver diseases. Cytochrome P450 enzymes catalyze various oxidative reactions in the human liver, intestine, kidney, lung, and central nervous system. They are involved in the metabolism of many endogenous and exogenous substrates, including drugs, toxins, hormones, and natural plant products. Antibodies against a particular cytochrome P450 isoenzyme, called anti-LKM (liver kidney microsome), have been identified in patients with autoimmune hepatitis type II and in a small number of patients with chronic hepatitis C.

CYTOMEGALOVIRUS ANTIBODY(CMV Ab)


Cytomegalovirus (CMV) is a common virus that may cause mononucleosis in healthy individuals or more severe disease in immunosuppressed persons. The presence of CMV antibody indicates recent infection or exposure. CMV infections in humans are widespread: 60% to 90% of adults have had CMV infection. Infection of healthy children and adults usually results in asymptomatic disease but can cause hepatitis or mononucleosis. If acquired in utero or at birth, CMV infection is usually asymptomatic, but in 10% of infants, it causes congenital abnormalities, including growth retardation, jaundice, hepatosplenomegaly, pneumonitis, and prematurity. CMV is a major cause of morbidity and mortality in immunosuppressed patients, who may develop pulmonary, gastrointestinal, or nervous system involvement.

DIHYDROEPIANDROSTERONE SULFATE(DHEA-S)


Dihydroepiandrosterone sulfate (DHEA-S) is a male hormone that is manufactured in the adrenal glands of both men and women. Its levels are abnormal in various glandular conditions. DHEA-S is a weak androgen secreted primarily by the zona reticularis of the adrenal cortex. Secretion is controlled by ACTH and other pituitary factors. Physiologically, DHEA-S has many roles, including the development of pubic and axillary hair, the development and maintenance of immunocompetence, and as a possible tumor marker. Serum levels of DHEA-S are 1,000 times greater than those of DHEA. Clinical indications for DHEA-S testing include hirsutism and amenorrhea (the most common sign of increased adrenal androgen production by women); polycystic ovarian syndrome (DHEA-S levels greater than 700-800 μg/dL in women are suggestive of a hormone-secreting adrenal tumor); and Cushing’s syndrome caused by an adrenal carcinoma (DHEA-S is usually not elevated if Cushing’s syndrome is caused by a benign adrenal tumor).

DIPHTHERIA TOXIN ANTIBODY


Diphtheria is an infectious disease caused by the toxin-producing bacterium Corynebacterium diphtheria. Presence of the antibody against Corynebacterium diphtheria indicates recent infection with, exposure to, or vaccination against diphtheria. Diphtheria is usually transmitted by contact with respiratory droplets from infected persons or asymptomatic carriers. It can also be transmitted by handling used tissues or using a glass or utensil used by an infected person. The incubation period is 2 to 5 days.

DOUBLE-STRANDED DNA ANTIBODY(dsDNA Ab)


Antibodies against the double-stranded DNA (dsDNA) in our own cells occur in various autoimmune and arthritis conditions. These antibodies are present in about 60% of patients with systemic lupus erythematosus, particularly those with associated nephritis, but are insufficient for diagnosing that condition. The dsDNA antibodies are also present in smaller fractions of patients with other rheumatic disorders, chronic active hepatitis, infectious mononucleosis, and biliary cirrhosis. There have been some reports of de novo development of dsDNA antibodies in patients with rheumatoid arthritis treated with infliximab (Remicade).

ENDOTHELIN 1(ET-1)


Endothelins are proteins that can powerfully constrict blood vessels. Their levels may be elevated in hypertension, chest pain (angina), and heart attack. Endothelins are also found in the central nervous system, and their levels may be elevated in conditions involving nervous system injury. Endothelins are extremely potent vasoconstrictors. Endothelin-1 is the most abundant and best characterized of three isoforms (ET-1, ET-2, and ET-3). In addition to vasoconstriction, endothelins affect neuronal excitability. Elevated plasma concentrations of endothelins have been observed in pulmonary hypertension, unstable angina, Prinzmetal’s angina, myocardial infarction, chronic heart failure, acute renal failure after renal ischemia, Raynaud’s disease, and Crohn’s disease.

EOSINOPHIL COUNT


This test measures the number of eosinophils in the blood. Eosinophils are a type of white blood cell whose levels are most commonly elevated in patients with allergies and parasitic infections. Eosinophils normally make up about 2.7% of the white blood cell count, but during eosinophilic leukocytosis, their numbers can increase by 5% to 90% (10% to 20% are most common). Eosinophils are active in allergic diseases (including asthma), parasitic infections, and other disorders, including eczema, leukemia, and autoimmune diseases. Medications that may cause an increase in eosinophils include amphetamines (appetite suppressants), tranquilizers, bulk-type laxatives containing psyllium, and certain antibiotics. Low numbers of eosinophils may be associated with alcohol intoxication or excessive production of adrenocorticosteroids.

EOSINOPHIL PERCENTAGE


This test measures the percentage of white blood cells that are eosinophils. Eosinophils are a type of white blood cell whose levels are most commonly elevated in patients with allergies and parasitic infections. The eosinophil percentage assesses the number of eosinophils in relation to other white blood cells.

EOTAXIN


Eotaxin is a protein produced by certain cells. Elevated levels of eotaxin may indicate allergic reaction or inflammation. Eotaxin is a chemokine characterized by its high chemotactic selectivity for eosinophils. It is produced by epithelial cells, endothelial cells, and eosinophils, and its expression is enhanced in allergic inflammation.

EPIDERMAL GROWTH FACTOR(EGF)


Epidermal growth factor (EGF) is a protein that stimulates cell growth (both normal and cancerous) and maturation. It is important in wound healing, but significant elevation of the levels of this protein may indicate cancer. Epidermal growth factor is a small mitogenic protein that is thought to be involved in normal cell growth, oncogenesis, and wound healing. The EGF receptor has been implicated in the development and progression of a number of human solid tumors including those of the lung, breast, prostate, colon, ovary, head, and neck.

EPITHELIAL NEUTROPHIL ACTIVATING PEPTIDE 78(ENA 78)


Epithelial neutrophil activating peptide 78 (ENA 78) is a protein found in abundance in the synovial fluid and blood of patients with rheumatoid arthritis. ENA 78 levels may also be elevated in patients with non-small cell lung cancer. The epithelial neutrophil activating peptide 78 is a potent chemoattractant and activator of neutrophil function and is produced by many non-hematopoietic cell types. ENA 78 is also expressed by epithelial cells in patients with Crohn’s disease, ulcerative colitis, acute appendicitis, and allergic airway inflammation.

EPSTEIN-BARR NUCLEAR ANTIGEN ANTIBODY(EBNA)


The presence of antibodies against Epstein-Barr virus (EBV) may indicate recent infection with or exposure to this virus. Primary EBV infection is shown by rising IgG-VCA (viral capsid antigen) antibody levels and the appearance of antibody to early antigen (EA). If both IgG-VCA and EBNA antibodies are present, past infection is indicated. Using the standard immunofluorescent test, EBNA antibodies are not seen in the acute phase but slowly appear 2 to 4 months after infection and persist for life. However, some EBNA enzyme immunoassays can detect antibody within a few weeks of infection.

EPSTEIN-BARR VIRAL CAPSID ANTIGEN ANTIBODY(VCA)


The presence of antibodies against Epstein-Barr virus may indicate recent infection with or exposure to this virus. Primary EBV infection is indicated if IgM antibody to the viral capsid antigen (VCA) is present and antibody to EBV nuclear antigen (EBNA) is absent. If VCA antibodies are not detected, the patient is susceptible to EBV infection. If antibodies to both VCA and EBNA are present, then past infection (from 4 to 6 months to years earlier) is indicated.

EPSTEIN-BARR VIRUS EARLY ANTIGEN ANTIBODY(EA)


Epstein-Barr virus (EBV) is a common cause of colds. When infection with EBV occurs during adolescence or young adulthood, it causes infectious mononucleosis 35% to 50% of the time. The presence of antibodies against EBV indicates recent infection or exposure. Infections due to Epstein-Barr virus (EBV) are very prevalent in most populations. Primary infection in young children is often asymptomatic or accompanied by nonspecific, minor illness. In adolescents or young adults, primary infection manifests 35% to 50% of the time as infectious mononucleosis, which is usually self-limiting and characterized by fever, sore throat, myalgias, lymphadenopathy, and hepatosplenomegaly. EBV has also been associated with a variety of disorders in persons with AIDS; post-transplant patients may develop EBV lymphoproliferative syndrome. As with other herpes viruses, EBV establishes a lifelong dormant infection in the immune system. Late events in a very few carriers of this virus include Burkitt’s lymphoma and nasopharyngeal carcinoma. Eighty percent of patients with active EBV infection produce antibody to early antigen (EA). In the presence of antibodies to Epstein-Barr nuclear antigen, antibodies to EA suggest reactivation. However, a positive EA test does not automatically indicate that a patient’s current medical condition is caused by EBV. Many healthy people with no symptoms have antibodies to EA for years after their initial EBV infection. Reactivation is often subclinical.

ERYTHROPOIETIN(EPO)


Erythropoietin (EPO) is a protein hormone produced in the kidneys that promotes the production of red blood cells in the bone marrow. Elevated levels of EPO may be seen in patients with most kinds of anemia, while low levels are seen in chronic renal failure as well as other chronic conditions. Renal production of EPO is regulated by changes in oxygen availability; under conditions of hypoxia, the level of EPO in the circulation increases, leading to increased production of RBCs. Primary polycythemias, such as polycythemia vera, are caused by EPO-independent growth of erythrocyte progenitors from abnormal stem cells, and low-to-normal EPO levels are found in the serum of affected patients. Various secondary polycythemias are associated with the production of higher than normal levels of EPO. The overproduction of EPO may be an adaptive response associated with conditions that produce tissue hypoxia, such as living at high altitude, chronic obstructive pulmonary disease, cyanotic heart disease, sleep apnea, high-affinity hemoglobinopathy, smoking, or localized renal hypoxia. In other instances, excessive EPO levels are the result of production by neoplastic cells. Deficient levels of EPO are found in conjunction with certain anemias, including anemia of renal failure and end-stage renal disease, anemias of chronic disorders, chronic infections, autoimmune diseases, rheumatoid arthritis, AIDS, malignancies, anemia of prematurity, anemia of hypothyroidism, and anemia of malnutrition.

ESTRADIOL


Estradiol is the most potent natural estrogen (the major female hormone). Estradiol is responsible for growth of the uterus, fallopian tubes, and vagina; breast development; maturation of the external genitals; deposition of body fat in a female distribution; and ending linear growth during adolescence. Estradiol also stimulates the proliferation of the uterine lining in the first half of the menstrual cycle. Estradiol levels are used to assess fertility, amenorrhea (lack of menstruation), and precocious puberty in girls. Estradiol (estradiol-17, E2) is the most potent natural estrogen and circulates in plasma predominantly in a protein-bound form. In non-pregnant women, E2 is produced mainly by the ovaries. In men, the testes and androgen precursors are the principal source. E2 determinations have proved of value in a variety of contexts, including the investigation of precocious puberty in girls and gynecomastia in men. Principal uses have been in the evaluation of amenorrhea and in the monitoring of ovulation induction.

ESTRIOL, UNCONJUGATED


One of the three major naturally occurring estrogens, estriol is a hormone that is produced almost exclusively during pregnancy (by the placenta). Estriol measurement is used to establish fetal status and placental function during pregnancy and may be useful as an early indicator of Down syndrome. Maternal serum unconjugated estriol levels increase rapidly following the first trimester. Estriol circulating in maternal blood has a short half-life of 20 to 30 minutes, and variations in the production of estriol by the feto-placental unit are reflected rapidly in maternal serum; thus maternal estriol levels usually fall dramatically immediately before intrauterine fetal death. Although low estriol levels may be seen in a variety of fetal problems, measurement has been most useful in diabetic mothers, post-date gestation, and intrauterine growth retardation. Estriol measurements in the second trimester may also be used as an indicator of Down syndrome.

FACTOR VII


Factor VII is one of many proteins involved in the process of normal blood coagulation. Factor VII levels are normally elevated when a blood vessel is injured and decreased in cases of Factor VII deficiency. In Factor VII deficiency disorders, it is present at lower levels than normal or may be completely absent. Inherited Factor VII deficiency is very rare, affecting only 1 in 1 million people, although 1 in 500 people may carry the defective gene. Acquired Factor VII deficiency (which may be temporary) is more common and may result from severe liver disease (Factor VII is produced in the liver) or low vitamin K levels due to medication use. In addition, acquired Factor VII deficiency is associated with certain forms of cancer and an autoimmune response to Factor VII.

FATTY ACID BINDING PROTEIN(FABP)


Fatty acid binding protein (FABP) may be significantly elevated in an acute heart attack. It is a newly introduced plasma marker of acute myocardial infarction (AMI), with some advantages over myoglobin and troponin-I. The normal FABP level is approximately 1.5 ng/ml and increases to 20 ng/ml or greater following AMI. As with myoglobin, elevated plasma concentrations are seen within 2 hours after AMI and generally return to normal within 18 to 24 hours. Because the concentration of FABP in skeletal muscle is 20 times lower than in cardiac tissue, however, FABP is more cardiac-specific than myoglobin. FABP also appears to be a useful plasma marker for the estimation of infarct size.

FERRITIN


Ferritin is a protein that stores iron in blood. Its levels may be useful in the evaluation of anemia and may also be elevated in inflammation or liver disease. Ferritin is found in serum in low concentrations that are directly proportional to the body’s total iron stores. Serum ferritin levels are very helpful in the evaluation of iron deficiency anemia, anemia of chronic infection, thalassemia, and hemochromatosis. However, ferritin levels can be nonspecifically elevated in patients with inflammation or liver disease, regardless of iron stores, due to hepatocellular leakage of ferritin from damaged cells.

FIBRINOGEN


Fibrinogen is a protein that is transformed into fibrin, which is an important protein in the coagulation of the blood. Abnormal levels of fibrinogen may be related to bleeding or clotting disorders. Cleavage of soluble fibrinogen by thrombin to form fibrin is the final common reaction of the coagulation cascade. Low levels of fibrinogen are seen in association with excessive fibrinogen use (as in disseminated intravascular coagulation), primary fibrinolysis, and liver disease. A high fibrinogen level is a risk factor for thrombosis and a strong predictor of cardiovascular risk and stroke, particularly in young adults. Low-dose heparin and ACE inhibitors reduce fibrinogen and the risk of cardiovascular events.

FIBROBLAST GROWTH FACTOR-BASIC FORM(FGF-BASIC)


Fibroblast growth factor-basic form (FGF-basic) is a protein factor that is produced by many cells. It is a powerful stimulant of new cell growth and may be involved in the development of plaques in blood vessels related to coronary heart disease. It is a heparin-binding growth factor that stimulates the proliferation of a variety of cells, including mesenchymal, neuroectodermal, and endothelial cells. It is a potent mitogen for arterial smooth muscle cells and plays a pivotal role in the pathogenesis of arteriosclerosis and restenosis. Human FGF-basic also exerts a potent angiogenic activity in vivo.

FOLIC ACID(ALSO CALLED FOLATE)


Folic acid (folate) is a B vitamin involved in many metabolic reactions in the body, including new cell growth. Maternal folic acid intake has been shown to reduce the risk of neural tube defects. Low levels of folic acid may be related to anemia, nutritional disorders, and metabolic disorders and may increase the risk of high blood pressure in women. Folates are compounds of pteroylglutamic acid (PGA) that function as coenzymes in metabolic reactions involving the transfer of single-carbon units from a donor to a recipient compound. Along with vitamin B12, folate is essential for the DNA synthesis required for normal RBC maturation. Obtained from dietary sources, folate is absorbed from the small intestine and stored in the liver. Low folate intake, malabsorption, pregnancy, chronic alcoholism, and drugs such as phenytoin can cause folate deficiency. Both folate and vitamin B12 deficiency can cause macrocytic anemia. Supplementary folic acid has also been shown to reduce the risk of incident hypertension, particularly in younger women.

FOLLICLE STIMULATING HORMONE(FSH)


Follicle stimulating hormone (FSH) is a sex hormone produced in the pituitary gland. In women, increased levels of FSH are associated with menopause or a decrease in ovarian function. Increased or decreased FSH levels are also associated with a variety of glandular conditions. Follicle stimulating hormone stimulates the growth of ovarian follicles and the production of estradiol during the first half of the menstrual cycle. In the male, it stimulates the epithelium of the seminiferous tubules and is partially responsible for inducing spermatogenesis. Increased levels of FSH are associated with menopause and primary ovarian hypofunction in females, primary hypogonadism in males, alcoholism, castration, and Turner’s and Klinefelter’s syndromes. Decreased FSH levels are associated with secondary or tertiary gonadal failure in females and males caused by anorexia nervosa, hemochromatosis, and/or pituitary tumors. They are also decreased in patients treated with estrogens or androgens.

GAMMA GLUTAMYL TRANSFERASE(GGT)


Gamma glutamyl transferase (GGT) is a liver enzyme whose levels may be elevated in conditions involving liver damage. GGT levels are useful in the evaluation of obstructive liver disease, since they are more organ-specific than alkaline phosphatase (ALP). They are also elevated in chronic alcoholics, when other tests are normal, and during antiepileptic therapy. Disproportionate elevation of both ALP and GGT indicates drug-induced cholestasis.

GASTRIN


Gastrin is a digestive hormone produced by the pancreas that stimulates the production of acid in the stomach. Gastrin levels are abnormal in a variety of diseases of the digestive tract and kidneys. Too much gastrin can cause severe peptic ulcer disease. Gastrin is secreted by the G-cells of the pancreas and stimulates the parietal cells of the fundus to produce gastric acid. It also stimulates gastrointestinal motility and the production of pepsinogens, intrinsic factor, secretin, pancreatic HCO3 and enzymes, and hepatic bile. Gastrin assays are helpful in the identification of Zollinger-Ellison tumors (gastrinomas) and other causes of hypergastrinemia. Hypergastrinemia may also occur in patients with normal or slightly increased gastric acid secretion, including patients with achlorhydria (atrophic gastritis or pernicious anemia), renal insufficiency, massive small bowel resection, G-cell hyperplasia, gastric outlet obstruction, and retained gastric antrum, as well as in patients receiving potent antisecretory drugs.

GLOBULIN(GLOB)


Globulins are roughly divided into alpha, beta, and gamma globulins. High globulin levels may indicate heart or liver disease or chronic inflammation, while low levels may indicate immune system dysfunction.

GLUCOSE


Most dietary carbohydrate is converted into glucose in the body. Glucose is a major source of energy for most body cells. Its blood level is regulated by insulin and a number of other hormones. Glucose levels are most commonly measured to diagnose diabetes or to monitor diabetes treatments. Blood glucose is regulated within narrow limits by insulin, but also by glucagon, cortisol, and epinephrine. Fasting glucose levels of >_ 126 mg/dL or 2-h postprandial glucose levels of >_ 200 mg/dL are supportive of the diagnosis of diabetes mellitus.

GLUTATHIONE S-TRANSFERASE(GST)


These enzymes are important in metabolizing various compounds, including drugs, and in detoxifying cancer-causing agents. Glutathione S-transferases are a family of multifunctional enzymes that use glutathione in reactions contributing to the transformation of a wide range of compounds, including carcinogens, therapeutic drugs, and products of oxidative stress, playing a key role in cellular detoxification.

GRANULOCYTE MACROPHAGE COLONY STIMULATING FACTOR(GM-CSF)


Granulocyte macrophage colony stimulating factor (GM-CSF) is a protein that stimulates the production of white blood cells that are important in fighting serious infection. Low levels of GM-CSF may be seen in patients prone to infection. GM-CSF is an acidic glycoprotein produced in response to a number of inflammatory mediators by mesenchymal cells in the hemopoietic environment and at peripheral sites of inflammation. GM-CSF stimulates the production of neutrophilic granulocytes, macrophages, and mixed granulocyte- macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from fetal liver progenitor cells. It can also affect some functional activities in mature granulocytes and macrophages. Clinically, recombinant GM-CSF is used to accelerate recovery from neutropenia and to prevent infection in cancer chemotherapy patients, AIDS patients, and persons with rare leukocyte disorders.

GROWTH HORMONE(GH)


Growth hormone (also called somatotropin) is a hormone produced in the anterior pituitary gland that regulates growth. This hormone is measured when there is abnormal growth in adults or children or when there is a history of a pituitary problem. Human growth hormone (GH, hGH, somatotropin) is the main regulator of somatic postnatal growth. It stimulates the release of somatomedin (also called IGF-I) by the liver, which causes growth. Basal GH levels in normal individuals are usually less than 2 ng/ml and are stable throughout the day. Normal elevations occur following meals, after exercise, and during sleep. Children who fail to grow at the expected rate and who have short stature with apparent normal body proportions often have a diminished capacity (congenital or acquired) to secrete growth hormone. Growth hormone deficiency in both adults and children may be the direct result of neoplastic or infiltrative disease of the pituitary or may follow cranial irradiation for brain tumors and other neoplasms.

HAPTOGLOBIN


Haptoglobin is a protein that binds to hemoglobin in the blood. Haptoglobin levels may be elevated in certain anemias, cancers, and acute inflammatory diseases. Decreased levels are seen in liver disease as well as certain anemias (hemolytic and sickle cell). It is an acute phase protein used in the detection of in vivo hemolysis. Its primary function is the irreversible binding of free oxyhemoglobin in plasma. This complex is then removed within minutes by the reticuloendothelial system, preventing loss of hemoglobin to urine and conserving iron.

HEAT SHOCK COGNATE PROTEIN 70 ANTIBODY(HSC-70)


Heat shock proteins (also called stress proteins) inside cells become more active when the cell is exposed to increased temperature or other kinds of cell stress (such as toxins, infection, or lack of oxygen). They have several functions that help the cell to recover from stress and repair stress-induced damage. Antibodies against these proteins may indicate that a patient is at increased risk of certain disorders. Functions of heat shock proteins (stress proteins) include stabilization and re-folding of proteins within the cell and various immunomodulatory activities outside it. Recent research indicates that they can induce pro-inflammatory responses and down-regulate pathogenic processes and may have a potential role as therapeutic agents. Heat shock protein 70 (HSP-70) belongs to a family of proteins that contains both heat-inducible and constitutively expressed members; the latter are sometimes called heat shock cognate proteins (HSCs). HSC-70 protein binds to nascent polypeptides to facilitate correct folding and functions as an ATPase in the disassembly of clathrin-coated vesicles during transport of membrane components through the cell.

HEAT SHOCK PROTEIN 32 ANTIBODY(HSP 32 Ab)


Heat shock proteins (also called stress proteins) inside cells become more active when the cell is exposed to increased temperature or other kinds of cell stress (such as toxins, infection, or lack of oxygen). They have several functions that help the cell to recover from stress and repair stress-induced damage. Antibodies against these proteins may indicate that a patient is at increased risk of certain disorders. Functions of heat shock proteins (stress proteins) include stabilization and re-folding of proteins within the cell and various immunomodulatory activities outside it. Recent research indicates that they can induce pro-inflammatory responses and down-regulate pathogenic processes and may have a potential role as therapeutic agents. Heat shock protein 32 appears to have a protective role in renal diseases such as glomerulonephritis and drug-induced nephrotoxicity.

HEAT SHOCK PROTEIN 65 ANTIBODY(HSP 65 Ab)


Heat shock proteins (also called stress proteins) inside cells become more active when the cell is exposed to increased temperature or other kinds of cell stress (such as toxins, infection, or lack of oxygen). They have several functions that help the cell to recover from stress and repair stress-induced damage. Antibodies against these proteins may indicate that a patient is at increased risk of certain disorders. Functions of heat shock proteins (stress proteins) include stabilization and re-folding of proteins within the cell and various immunomodulatory activities outside it. Recent research indicates that they can induce pro-inflammatory responses and down-regulate pathogenic processes and may have a potential role as therapeutic agents. Elevated levels of circulating antibody to heat shock protein 65 have been reported in carotid atherosclerosis, coronary heart disease, and borderline hypertension, but the physiological significance of these antibodies is not yet well understood.

HEAT SHOCK PROTEIN 71 ANTIBODY(HSP 71 Ab)


Heat shock proteins (also called stress proteins) inside cells become more active when the cell is exposed to increased temperature or other kinds of cell stress (such as toxins, infection, or lack of oxygen). They have several functions that help the cell to recover from stress and repair stress-induced damage. Antibodies against these proteins may indicate that a patient is at increased risk of certain disorders. Functions of heat shock proteins (stress proteins) include stabilization and re-folding of proteins within the cell and various immunomodulatory activities outside it. Recent research indicates that they can induce pro-inflammatory responses and down-regulate pathogenic processes and may have a potential role as therapeutic agents. Elevated levels of circulating antibody to heat shock protein 71 have been observed in children with immune thrombocytopenic purpura and in adults with acute heat-induced illnesses (heat cramps, heat stroke, and heat exhaustion) and benzene poisoning.

HEAT SHOCK PROTEIN 90 ALPHA ANTIBODY(HSP 90 ALPHA Ab)


Heat shock proteins (also called stress proteins) inside cells become more active when the cell is exposed to increased temperature or other kinds of cell stress (such as toxins, infection, or lack of oxygen). They have several functions that help the cell to recover from stress and repair stress-induced damage. Antibodies against these proteins may indicate that a patient is at increased risk of certain disorders. Functions of heat shock proteins (stress proteins) include stabilization and re-folding of proteins within the cell and various immunomodulatory activities outside it. Recent research indicates that they can induce pro-inflammatory responses and down-regulate pathogenic processes and may have a potential role as therapeutic agents. Elevated levels of circulating antibody to heat shock protein 90 alpha have been seen in individuals with acute heat-induced illnesses (heat cramps, heat stroke, and heat exhaustion), breast cancer, late-stage ovarian cancer, Guillain-Barré syndrome, graft-versus-host disease, systemic lupus erythematosus, and lupus nephritis, among other disorders.

HELICOBACTER PYLORI IgG ANTIBODY(H. PYLORI IgG Ab)


Helicobacter pylori (H. pylori IgG) is a bacterium responsible for the majority of stomach ulcers and many cases of chronic gastritis. Antibodies against H. pylori indicate prior infection with this bacterium. H. pylori, a common and normal inhabitant of the mucus layer of the human stomach, plays an important role in gastroduodenal inflammatory and neoplastic diseases. H. pylori antibodies are detectable in almost all adult patients with duodenal ulcers and in about 80% of patients with gastric ulcers. Infection occurs through person-to-person contact or contaminated water or food. The prevalence of H. pylori antibodies increases with age; they are more commonly found in developing countries with poor sanitation.

HEMATOCRIT


The hematocrit is the percentage of whole blood that comprises red blood cells. It is a measure of both the number and the size of these cells and is expressed as a percentage by volume. The normal ranges are age-dependent up to adolescence and gender-dependent after adolescence. A low hematocrit may indicate anemia, blood loss, bone marrow failure, destruction of red blood cells, malnutrition or specific nutritional deficiency, multiple myeloma, or rheumatoid arthritis. A high hematocrit may indicate dehydration due to burns or diarrhea, eclampsia, erythrocytosis, or polycythemia vera.

HEMOGLOBIN(Hb)


Hemoglobin (Hb) is an iron-containing protein that enables red blood cells to carry oxygen to tissues. Low levels of hemoglobin may indicate anemia, excessive bleeding, or nutritional deficiencies. It is a tetrameric hemoprotein found in erythrocytes, consisting of approximately 3.8% heme and 96.2% globin. As oxyhemoglobin (HbO2), it transports oxygen from the lungs to the tissues where the oxygen is readily released, and HbO2 becomes Hb. Disorders of Hb synthesis include structurally abnormal hemoglobins (hemoglobinopathies, the most common being sickle cell anemia) and thalassemias (in which structurally normal hemoglobins are synthesized at a lower rate, or not at all).

HEMOGLOBIN A1c(HbA1c)


Hemoglobin A1c (HbA1c) measures the amount of glucose bound to hemoglobin and indicates the general control of glucose levels in a diabetic patient over 2 to 3 months. HbA1c, also known as glycated hemoglobin or glycosylated hemoglobin, is formed when glucose in the blood binds irreversibly to hemoglobin to form a stable complex. Since the normal life span of erythrocytes is 90 to 120 days, HbA1c is eliminated only when red cells are replaced. Thus, HbA1c values are directly proportional to the concentration of glucose in the blood over the full life span of the red blood cells and are not subject to the fluctuations seen with daily blood glucose monitoring. In patients with uncontrolled diabetes, the ratio of HbA1c to non-glycated hemoglobin is higher than in non-diabetics or diabetics with good glucose control.

HEPATITIS A ANTIBODY(HAV-Ab)


Hepatitis A (HAV-Ab) is a virus that causes infectious hepatitis (inflammation of the liver). The presence of the antibody to hepatitis A virus indicates recent infection or exposure. Hepatitis A virus (HAV) is a small RNA virus belonging to the Picornaviridae family. It is spread primarily through food or water contaminated by feces from an infected person and rarely through contact with infected blood. It can cause widespread outbreaks of disease or sporadic cases of acute hepatitis, which usually resolve without treatment over several weeks. Hepatitis A outbreaks can occur among intravenous drug users, homosexual men, and hemophiliacs receiving Factors VIII and IX concentrates. Hepatitis A has an incubation period of about 4 weeks, is generally mild to moderate in severity (and usually asymptomatic in young children), and never becomes chronic. Most of the rare cases of acute liver failure due to HAV are associated with older age or underlying chronic liver disease. HAV-specific IgM antibodies are almost always present by the time symptoms of acute hepatitis appear.

HEPATITIS B CORE ANTIBODY(ANTI-HBc)


The body produces hepatitis B core IgM antibody (Anti-HBc) in response to the core antigen, but the antibody does not have a protective role in defense against the virus. Hepatitis B core antigen is derived from the protein envelope that encloses the viral DNA. A positive hepatitis B core IgM antibody test indicates past or present infection with hepatitis B but could also be a false- positive. Interpretation of this test result depends on the results of the hepatitis B surface antigen test. Its appearance with the protective surface antibody (HbsAb) indicates prior infection and recovery. In chronically infected persons, it will usually appear with the surface antigen (HbsAg).

HEPATITIS B e ANTIBODY(ANTI-HBe)


Hepatitis B e antigen is closely associated with the nucleocapsid of hepatitis B virus. Hepatitis B e antibody (anti-HBe) is the antibody that is produced in response to this antigen. During the acute stage of infection, the seroconversion from e antigen to e antibody is prognostic for resolution of infection. Presence of anti-HBe in serum along with anti-HBc and the absence of HBs antigen and anti-HBs indicate low contagiousness and convalescence.

HEPATITIS B SURFACE ANTIBODY(ANTI-HBs)


Hepatitis B surface antigens are molecules on the outer surface of the hepatitis B virus that trigger an antibody response. Hepatitis B surface antibody (anti-HBs) is the specific antibody to hepatitis B surface antigen. Anti-HBs in serum within 1 to 4 months after onset of symptoms indicate clinical recovery. Anti-HBs can provide protection against hepatitis B infection.

HEPATITIS B SURFACE ANTIGEN(HBsAg)


Hepatitis B surface antigens (HBsAg) are molecules on the outer surface of the hepatitis B virus that trigger an antibody response. A positive HBsAg test result indicates infection with the hepatitis B virus. Persistent presence of this antigen may indicate chronic infection. Hepatitis B virus (HBV) belongs to the Hepadnaviridae family. Most cases are transmitted through transfusion of HBV-contaminated blood and blood products, sexual contact, or from mother to newborn at birth. It can also be transmitted via needle sticks, body piercing, and tattooing using unsterilized instruments. HBsAg is the first serological marker detected, at a mean of 4 to 12 weeks after exposure, and levels peak before onset of symptoms. It is usually present for 2 to 3 months, but 5% to 10% of patients will have persistent HBsAg levels beyond 6 months (chronic carriers).

HEPATITIS C ANTIBODY


Hepatitis C virus (HCV) is generally transmitted through contact with infected blood products. The presence of the antibody against hepatitis C indicates recent infection or exposure. Hepatitis C virus, an RNA virus belonging to a distinct genus in the Flaviviridae family, is transmitted most efficiently via a parenteral route and is the most common chronic blood-borne infection in the United States. Blood transfusions were the leading route of transmission until routine blood screening began in 1991. In the U.S., most newly acquired hepatitis C infections are related to intravenous drug use. Risk of sexual transmission is low and occurs in < 5% of those couples in which one individual is infected. Mother-to-baby transmission is possible, but uncommon. Acute hepatitis C is asymptomatic in a majority of cases but results in chronic infection in 80% to 85% of patients. Hepatitis C is the most important cause of chronic liver disease in the U.S., with an estimated 3.9 million HCV-infected individuals. Clinical manifestations of chronic infection vary greatly; about 10% of patients develop liver cirrhosis over a 20-year period, and these patients are at risk for hepatocellular carcinoma. For those exposed to hepatitis C, the pattern of antibody formation is the primary method to assess the stage of disease.

HEPATITIS D ANTIBODY


Hepatitis D virus is strongly associated with hepatitis B virus infections. The presence of the antibody against hepatitis D indicates recent infection or exposure. Infection with the hepatitis delta virus (hepatitis delta-agent, HDV) is always seen in association with hepatitis B virus (HBV) infection, either as a simultaneous acute infection or as an acute super-infection superimposed upon chronic HBV hepatitis. HDV is an RNA virus that requires the presence of HBV for viral replication to occur. Patients almost invariably have detectable hepatitis B surface antigen (HBsAg) and/or antibodies to hepatitis core antigen (anti-HBc) and hepatitis B e antigen. In patients with acute co-infections, hepatitis D antigen (HDVAg) appears early after HBsAg and disappears with convalescence. Acute HDV infections are associated with anti-HDV IgM antibody, and chronic cases usually only demonstrate IgG antibody. Both antibodies may eventually disappear following convalescence.

HEPATITIS E orf 2.3 kD ANTIBODY(HEV orf 2.3 kD Ab)


Hepatitis E virus (HEV) is a major cause of water-borne acute hepatitis in Asia, Africa, and Mexico. The presence of the antibody against hepatitis E virus indicates recent infection or exposure. HEV transmission is via the fecal-oral route, presumably through contaminated water supplies; it often occurs among individuals 15 to 40 years of age and is usually not chronic. The highest rate of symptomatic disease (jaundice) occurs in hepatitis E outbreaks. Subclinical, non-icteric forms are rare but possible. Sporadic cases of hepatitis E in industrialized, non-endemic countries are occasionally reported. The incubation period following HEV exposure ranges from 15 to 60 days. In endemic areas, fulminant hepatitis due to HEV is highly associated with pregnancy, particularly with infections during the third trimester of pregnancy. Maternal hepatitis E fatality can reach 40%, while in the general population, the mortality rate for acute HEV infection is 0.5% to 4.0%. The duration of anti-HEV IgG persistence and the natural history of protective immunity to HEV are not well-known.

HEPATITIS E orf 2.6 kD ANTIBODY(HEV orf 2.6 kD Ab)


Hepatitis E virus (HEV) is a major cause of water-borne acute hepatitis in Asia, Africa, and Mexico. The presence of the antibody against hepatitis E virus indicates recent infection or exposure. HEV transmission is via the fecal-oral route, presumably through contaminated water supplies; it often occurs among individuals 15 to 40 years of age and is usually not chronic. The highest rate of symptomatic disease (jaundice) occurs in hepatitis E outbreaks. Subclinical, non-icteric forms are rare but possible. Sporadic cases of hepatitis E in industrialized, non-endemic countries are occasionally reported. The incubation period following HEV exposure ranges from 15 to 60 days. In endemic areas, fulminant hepatitis due to HEV is highly associated with pregnancy, particularly with infections during the third trimester of pregnancy. Maternal hepatitis E fatality can reach 40%, while in the general population, the mortality rate for acute HEV infection is 0.5% to 4.0%. The duration of anti-HEV IgG persistence and the natural history of protective immunity to HEV are not well-known.

HEPATITIS E orf 3.3 kD ANTIBODY(HEV orf 3.3 kD Ab)


Hepatitis E virus (HEV) is a major cause of water-borne acute hepatitis in Asia, Africa, and Mexico. The presence of the antibody against hepatitis E virus indicates recent infection or exposure. HEV transmission is via the fecal-oral route, presumably through contaminated water supplies; it often occurs among individuals 15 to 40 years of age and is usually not chronic. The highest rate of symptomatic disease (jaundice) occurs in hepatitis E outbreaks. Subclinical, non-icteric forms are rare but possible. Sporadic cases of hepatitis E in industrialized, non-endemic countries are occasionally reported. The incubation period following HEV exposure ranges from 15 to 60 days. In endemic areas, fulminant hepatitis due to HEV is highly associated with pregnancy, particularly with infections during the third trimester of pregnancy. Maternal hepatitis E fatality can reach 40%, while in the general population, the mortality rate for acute HEV infection is 0.5% to 4.0%. The duration of anti-HEV IgG persistence and the natural history of protective immunity to HEV are not well-known.(HEV orf 3.3 kD Ab)

HERPES SIMPLEX VIRUS TYPE 1 GLYCOPROTEIN D ANTIBODY(HSV-1 gD Ab)


Antibodies to herpes simplex virus type 1 (HSV-1) glycoprotein D indicate exposure to the most common herpes virus, which primarily causes the common cold sore, although it infrequently infects other mucous membranes. About 80% of adults carry these antibodies.

HERPES SIMPLEX VIRUS TYPES 1 AND 2 ANTIBODIES(HSV-1/2 Ab)


Herpes simplex virus type 1 (HSV-1) is the virus that causes cold sores, while herpes simplex virus type 2 (HSV-2) causes genital herpes. The presence of antibodies to either of these viruses indicates that the individual has been exposed to that virus. HSV-1 and HSV-2 can both cause systemic disease in an immunodeficient person. Antibody testing demonstrates whether an individual has been exposed to either of these viruses.

HERPES SIMPLEX VIRUS TYPE 2 GLYCOPROTEIN D ANTIBODY(HSV-2 gD Ab)


Herpes simplex virus type 2 (HSV-2) is the virus that causes genital herpes. Antibodies to HSV-2 glycoprotein D indicate exposure to the herpes virus most commonly responsible for genital infection. About 25% of adults carry these antibodies.

HIGH-DENSITY LIPOPROTEIN(HDL)


Cholesterol carried by HDL is known as the “good cholesterol” because higher levels of HDL-cholesterol are associated with a lower risk for coronary heart disease. About 25% to 30% of blood cholesterol is transported by HDL particles. By carrying excess cholesterol to the liver for “re-packaging” or excretion in the bile, HDLs help to prevent cholesterol deposition in the arteries. Low levels of HDL-cholesterol are associated with an increased risk of heart disease. Women tend to have higher HDL-cholesterol levels than men. The total cholesterol/HDL ratio is more useful in the determination of cardiovascular risk than is total cholesterol.

HISTONE ANTIBODY


Histones are normal proteins associated with the DNA in the nuclei of our cells. Antibodies to histones may be elevated in drug-induced lupus erythematosus. Autoantibodies to histones (typically IgG) occur in drug- induced lupus (DIL) in the absence of other autoantibodies and are especially reactive with histone H2A-H2B dimers when induced by procainamide. Histone autoantibody concentrations often decrease when the culprit drug is avoided. Broadly reactive histone H1-H4 autoantibodies of the IgM isotype are common in systemic lupus erythematosus (SLE) and in asymptomatic individuals taking various medications. DIL due to procainamide, quinidine, acebutolol, penicillamine, and isoniazid, but not methyldopa, can be accompanied by autoantibodies to histone (H2A-H2B)-DNA complexes. Histones H2A and H2B (as well as H1, H3, and H4) are recognized by separate populations of histone autoantibodies in SLE, DIL, juvenile rheumatoid arthritis, and other syndromes.

HISTONE H1 ANTIBODY


Antibodies to histones may develop in drug-induced lupus erythematosus. This is a form of autoimmune disease. Histone autoantibody concentrations often decrease when the culprit drug is avoided. Broadly reactive histone H1-H4 autoantibodies of the IgM isotype are common in systemic lupus erythematosus (SLE) and in asymptomatic individuals taking various medications. Histones H1, H2A, H2B, H3, and H4 are recognized by separate populations of histone autoantibodies in SLE, DIL, juvenile rheumatoid arthritis, and other syndromes.

HISTONE H2A ANTIBODY


Histones are normal proteins associated with the DNA in the nuclei of our cells. Autoantibodies to histones (typically IgG) occur in drug-induced lupus (DIL) in the absence of other autoantibodies and are especially reactive with histone H2A-H2B dimers when induced by procainamide. Histone autoantibody concentrations often decrease when the culprit drug is avoided. Broadly reactive histone H1-H4 autoantibodies of the IgM isotype are common in systemic lupus erythematosus (SLE) and in asymptomatic individuals taking various medications. DIL due to procainamide, quinidine, acebutolol, penicillamine, and isoniazid, but not methyldopa, can be accompanied by autoantibodies to histone (H2A-H2B)-DNA complexes. Histones H2A and H2B (as well as H1, H3, and H4) are recognized by separate populations of histone autoantibodies in SLE, DIL, juvenile rheumatoid arthritis, and other syndromes. Histone (H2A-H2B)-DNA complex autoantibodies react strongly with native chromatin and are present in significantly fewer American SLE patients (50%) than Asian SLE patients (70%). They are also present in patients with scleroderma-related diseases. In procainamide-induced lupus, the sensitivity of IgG histone (H2A-H2B)-DNA complex autoantibodies is 84% at the time of diagnosis, but substantially lower after immunosuppressive or anti-inflammatory treatment.

HISTONE H2B ANTIBODY


Histones are normal proteins associated with the DNA in the nuclei of our cells. Autoantibodies to histones (typically IgG) occur in drug-induced lupus (DIL) in the absence of other autoantibodies and are especially reactive with histone H2A-H2B dimers when induced by procainamide. Histone autoantibody concentrations often decrease when the culprit drug is avoided. Broadly reactive histone H1-H4 autoantibodies of the IgM isotype are common in systemic lupus erythematosus (SLE) and in asymptomatic individuals taking various medications. DIL due to procainamide, quinidine, acebutolol, penicillamine, and isoniazid, but not methyldopa, can be accompanied by autoantibodies to histone (H2A-H2B)-DNA complexes. Histones H2A and H2B (as well as H1, H3, and H4) are recognized by separate populations of histone autoantibodies in SLE, DIL, juvenile rheumatoid arthritis and other syndromes. Histone (H2A-H2B)-DNA complex autoantibodies react strongly with native chromatin and are present in significantly fewer American SLE patients (50%) than Asian SLE patients (70%). They are also present in patients with scleroderma-related diseases. In procainamide-induced lupus, the sensitivity of IgG histone (H2A-H2B)-DNA complex autoantibodies is 84% at the time of diagnosis, but substantially lower after immunosuppressive or anti-inflammatory treatment.

HISTONE H3 ANTIBODY


Histones are normal proteins associated with the DNA in the nuclei of our cells. Antibodies to histones may develop in drug-induced lupus erythematosus. Autoantibodies to histones (typically IgG) occur in drug-induced lupus (DIL) in the absence of other autoantibodies and are especially reactive with histone H2A-H2B dimers when induced by procainamide. Histone autoantibody concentrations often decrease when the culprit drug is avoided. Broadly reactive histone H1-H4 autoantibodies of the IgM isotype are common in systemic lupus erythematosus (SLE) and in asymptomatic individuals taking various medications. Histones H1, H2A, H2B, H3, and H4 are recognized by separate populations of histone autoantibodies in SLE, DIL, juvenile rheumatoid arthritis, and other syndromes.

HISTONE H4 ANTIBODY


Histones are normal proteins associated with the DNA in the nuclei of our cells. Antibodies to histones may develop in drug-induced lupus erythematosus. Autoantibodies to histones (typically IgG) occur in drug-induced lupus (DIL) in the absence of other autoantibodies and are especially reactive with histone H2A-H2B dimers when induced by procainamide. Histone autoantibody concentrations often decrease when the culprit drug is avoided. Broadly reactive histone H1-H4 autoantibodies of the IgM isotype are common in systemic lupus erythematosus (SLE) and in asymptomatic individuals taking various medications. Histones H1, H2A, H2B, H3, and H4 are recognized by separate populations of histone autoantibodies in SLE, DIL, juvenile rheumatoid arthritis, and other syndromes.

HOMOCYSTEINE


Homocysteine is an amino acid found in the blood, the elevation of which may increase the risk for coronary heart disease. Homocysteine is a sulfur- containing amino acid that exists in both free (trace) and bound (98% to 99%) forms in the blood. Impaired enzyme function, as a result of genetic mutations or deficiency of essential vitamin cofactors, can lead to elevated homocysteine concentrations in circulation. Elevation of the level of homocysteine in the plasma has been linked to cardiovascular disease (including myocardial infarction, stroke, thromboembolic disease, and intermittent claudication), even in people with normal cholesterol levels, and (in pregnant women) to fetal neural tube defects. It is important to note, however, that a causal link between elevated homocysteine and these disorders has not been established.

HUMAN CHORIONIC GONADOTROPIN(Beta-hCG)


Beta human chorionic gonadotropin (Beta-hCG) is a hormone whose levels become elevated early in pregnancy (1 to 2 days after implantation of the fertilized egg in the uterus or about 10 days after ovulation). The test is most often used to confirm a pregnancy, but serum beta-hCG may also be increased in women with certain types of ovarian tumors or in men with testicular tumors. Blood or urine beta-hCG tests usually suffice for detection of normal pregnancy when it has progressed about 10 days beyond ovulation. Produced by the placental trophoblastic cells, beta-hCG’s most important role appears to be stimulation of ovarian secretion of the estrogen and progesterone required for the integrity of conceptus during the first trimester. Beta-hCG levels drop at the beginning of the second trimester as the placenta begins to produce enough progesterone to maintain the endometrium. Elevated levels of beta- hCG may indicate choriocarcinoma of the uterus, hydatidiform mole of the uterus, normal pregnancy, ovarian cancer, or testicular cancer. False-positive results occur in men with solitary testes.

HUMAN PAPILLOMA VIRUS ANTIBODY(HPV Ab)


Human papilloma virus (HPV) is the most commonly sexually transmitted organism. It is the cause of genital warts and may increase the risk of cervical cancer. The presence of the antibody to HPV indicates recent infection with the virus. HPV is an icosahedral DNA virus of the genus Papillomavirus, family Papovaviridae. Many serotypes have been described; some cause cutaneous and genital warts, while others are associated with severe cervical intraepithelial neoplasia and anogenital and laryngeal carcinomas. Exposure to HPV can be determined by testing the serum for antibodies to the viral capsule. Exposure to one serotype does not prevent infection from another; in fact, one study looking at seropositivity to HPV type 16 found a 30% incidence of multiple HPV type positivity.

HUMAN T-CELL LYMPHOTROPIC VIRUS TYPES 1 AND 2 ANTIBODIES(HTLV-1/2 Ab)


Human T-cell lymphotropic virus (HTLV) is a virus that may be associated with T-cell leukemias and lymphomas. The presence of antibodies against HTLV-1 or HTLV-2 may indicate exposure or infection. Human T-lymphotropic virus types 1 (HTLV-1) and 2 (HTLV-2) differ in pathogenicity. HTLV-1 causes leukemia and other neurologic and inflammatory diseases, whereas HTLV-2 is less clearly associated with specific diseases. HTLV antibodies have been detected in family members of patients with HTLV-associated disease.

IMMUNOGLOBULIN A(IgA)


Secretory immunoglobulin A (IgA) is found in tears, sweat, saliva, mother’s milk and colostrum, and in gastrointestinal and bronchial secretions. It protects the mucosa from bacteria and viruses. The presence of secretory IgA also affects the development of allergic (IgE) reactions to various ingested antigens by binding the antigens and preventing IgE responses. Elevated serum IgA is common in patients with skin, gut, respiratory, and renal infections, or AIDS. IgA (and sometimes IgG) are also elevated in portal cirrhosis. IgA deficiency is found in 1 in 750 individuals.

IMMUNOGLOBULIN E(IgE)


Immunoglobulin E (IgE) antibodies are a class of proteins that are often involved in allergic reactions. Significant elevations in IgE levels may indicate an allergic reaction, parasitic infection, or immune disorder. The levels of circulating IgE in serum are low (<0.1%) compared with levels of the other immunoglobulins. Levels at birth are almost non-detectable but increase with age. Serum IgE levels are elevated in individuals with multiple myeloma and severe allergic reactions, and IgE serum assays are useful in monitoring treatment of these disorders. However, low levels of circulating IgE do not necessarily indicate the absence of allergic disease, since certain individuals have low total IgE levels but a high concentration of allergen-specific IgE. Investigators have shown that increased IgE levels in cord blood and infant’s serum may predict the early onset of allergic disease. Patients with pulmonary aspergillosis, parasitic infestations, and some immunodeficiencies have also been found to have elevated IgE levels.

IMMUNOGLOBULIN M(IgM)


IgM antibodies are a class of proteins produced by the immune system early in an immune reaction. IgM levels therefore usually rise in acute infections, particularly viral infections. Substantially elevated serum IgM levels may indicate a variety of blood cell disorders. In adults, IgM accounts for about 10% of the total serum antibodies. IgM deficiency may be due to protein loss, primary inherited defects, toxins (e.g., drugs or substances retained in renal failure), or secondary to lymphoid malignancies. IgM antibodies tend to predominate in primary viral infections and bloodstream infections (e.g., malaria), and IgM levels are markedly increased in primary biliary cirrhosis. In intrauterine infections, fetal production of IgM increases, and at birth, IgM levels in cord blood are increased. High levels of plasma IgM are also seen in patients with Waldenström’s macroglobulinemia and monoclonal cryoglobulinemias.

INFLUENZA A ANTIBODY


Influenza is a viral disease characterized by fever, muscle aches, headache, sore throat, fatigue, and sometimes cough. Influenza type A is the most common type of virus to cause “the flu.” The presence of antibodies to influenza A indicates exposure to or infection with this virus. Levels of these antibodies may be elevated after getting the flu vaccine. Influenza type A virus can infect a wide variety of animals, including horses, poultry, and swine. Of the three types of influenza viruses, type A is most likely to cause epidemics and pandemics because it can undergo antigenic drift (gradual viral evolution) and shift (abrupt changes in viral hemagglutinin and/or neuraminidase proteins) and present a new immune target to susceptible individuals. The influenza A antibody test determines whether exposure to or vaccination with influenza A has occurred.

INFLUENZA A H3N2 ANTIBODY


Influenza is a viral disease characterized by fever, muscle aches, headache, sore throat, fatigue, and sometimes cough. Influenza type A is the most common type of virus to cause “the flu,” and H3N2 is a common subtype of this virus. The presence of antibodies to influenza A H3N2 indicates recent exposure to or infection with this virus. Levels of these antibodies may be elevated after getting the flu vaccine. Influenza type A virus can infect a wide variety of animals, including horses, poultry, and swine. Of the three types of influenza viruses, type A is most likely to cause epidemics and pandemics because it can undergo antigenic drift (gradual viral evolution) and shift (abrupt changes in viral hemagglutinin and/or neuraminidase proteins) and present a new immune target to susceptible individuals. Type A viruses are divided into subtypes based on differences in hemagglutinin and neuraminidase proteins; current subtypes are designated A (H2N1) and A (H3N2). This test determines whether exposure to or vaccination with influenza A, subtype H3N2, has occurred.

INFLUENZA B ANTIBODY


Influenza is a viral disease characterized by fever, muscle aches, headache, sore throat, fatigue, and sometimes cough. Influenza type A and influenza type B are common viruses that can cause “the flu.” Although both types may cause widespread infection, influenza B infections are often limited to localized outbreaks. The presence of antibodies to influenza B indicates exposure to or infection with this virus. Levels of these antibodies may be elevated after getting the flu vaccine. Influenza type B virus infects only humans and can cause widespread disease. However, since this virus undergoes relatively slow changes in viral hemagglutinin proteins (unlike the type A virus), it is less frequently the cause of influenza epidemics. Nonetheless, influenza B virus is currently included in the influenza vaccine, and antibody levels may be elevated following vaccination. The pattern of antibody to the various serotypes of influenza can provide useful information regarding the history of exposure.

INSULIN


Insulin is a hormone made by the pancreas that regulates the amount of sugar (glucose) in the blood and allows cells to use this sugar for energy. Diabetes occurs when the body fails to produce enough insulin or when the body’s cells cannot respond to it efficiently. Insulin levels may be monitored in patients suspected of having low blood sugar (hypoglycemia) or high insulin levels (hyperinsulinemia), the latter being common in certain diseases, including insulin resistance syndrome and polycystic ovarian syndrome. Insulin circulates in inappropriately high levels in patients with insulin-secreting pancreatic tumors (insulinomas) resulting in hypoglycemia. Accordingly, insulin immunoassays, sometimes used in connection with a provocative dose of tolbutamide or calcium, play an essential role in the identification (and localization) of these tumors. Diabetes, obesity, a high-carbohydrate diet, and inactivity all tend to increase insulin levels, and elevated levels are found in acromegaly, Cushing’s syndrome, thyrotoxicosis, and polycystic ovarian syndrome.

INSULIN ANTIBODY


Antibodies against insulin may develop in patients receiving insulin injections for the treatment of diabetes. This may make them somewhat resistant to insulin’s effects. In patients who have never received insulin injections, antibodies against insulin may indicate an autoimmune condition leading to the destruction of the insulin-producing cells in the pancreas. This could result in the development of diabetes. The presence of insulin autoantibodies (antibodies against insulin in patients never treated with it) is evidence of the ongoing destruction of islet cells. When present in sufficient quantities, insulin antibodies can cause insulin resistance or stimulate inappropriate insulin release. Insulin antibody levels are useful when a change in insulin source is being considered or when the patient is not responding predictably to insulin therapy.

INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN 3(IGFBP3)


IGF binding protein 3 is a protein hormone whose structure resembles that of insulin. Functionally, it is related to growth hormone and may be important in the normal development of children. Insulin-like growth factors (IGF-1 and IGF-2) are peptides structurally similar to insulin, which exhibit growth- promoting as well as insulin-like and mitogenic effects. Circulating IGF-1 is almost totally bound to IGF binding proteins (IGFBPs), 6 of which have been identified. IGFBP3 is the major carrier of IGFs in serum and is present in the highest concentrations. Serum concentrations are fairly constant throughout the day and are controlled by growth hormone (GH) and IGF-1 levels. The measurement of IGFBP3 is useful in the evaluation of short stature in children, acromegaly, the efficacy of treatment for GH deficiency, the surgical cure of somatotroph tumors, and nutritional status. Because IGFBP3 levels are less age-dependent (and higher in young children) than IGF-1 levels, they allow for better differentiation between normal and subnormal levels. IGFBP3 levels also show a better correlation with GH sufficiency than do single measurements of IGF-1 or IGF-2. Although originally defined as the principal carrier of IGF-1 in the circulation and the primary regulator of the amount of free IGF-1 available to interact with the IGF-1 receptor, evidence is accumulating that IGFBP3 can also cause apoptosis in an IGF-independent manner, suggesting that its ultimate function may be to protect against the potentially carcinogenic effects of growth hormone and IGF-1.

INSULIN-LIKE GROWTH FACTOR-1(IGF-1)


Insulin-like growth factor-1 (IGF-1) is a protein hormone similar in structure and function to insulin, but with a much higher growth-promoting activity than insulin. It stimulates proliferation and survival of various cell types including muscle, bone, and cartilage tissue in vitro. IGFs are predominantly produced in the liver, although a variety of tissues produce IGFs at distinctive times. Circulating IGF-1 is almost totally protein-bound to IGF binding proteins (IGFBPs).

INTERCELLULAR ADHESION MOLECULE-1(ICAM-1)


Intercellular adhesion molecule-1 (ICAM-1) is a cell surface adhesion molecule whose levels may be elevated in several diseases, including chronic inflammatory conditions, cardiovascular disease, HIV, asthma, diabetes, and cancer. ICAM-1 (also called CD54) is a cell surface adhesion molecule that is implicated in a number of cellular processes. It can be expressed on non-hematopoietic cells, including vascular endothelial cells, thymic epithelial cells, other epithelial cells, and fibroblasts, as well as on hematopoietic cells such as tissue macrophages, mitogen-stimulated T-lymphoblasts, germinal center B-cells, and dendritic cells in the tonsils, lymph nodes, and Peyer’s patches. Its soluble form is a product of cleavage at the cell’s surface and may have either positive or negative feedback functions.

INTERLEUKIN-1 ALPHA(IL-1 ALPHA)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-1 alpha (IL-1 alpha) controls certain immune system reactions, including inflammation, swelling, fever, and shivering. IL-1 stimulates T-cells to secrete IL-2 and activate the inflammatory response. It also causes the hypothalamus to increase the body temperature. The two distinct forms of the protein, IL-1 alpha and IL-1 beta, perform the same functions but are structurally quite distinct. Biological effects of IL-1 include replacing macrophage requirements for T-cell activation, inducing fever and shivering, promoting prostaglandin production, promoting leukocyte growth, augmenting corticosteroid release, promoting hematopoesis, and promoting wound healing. Peripheral blood mononuclear cells of patients with aplastic anemia show markedly decreased IL-1 levels, although myelodysplastic patients with comparable degrees of pancytopenia have normal IL-1 production. Elevated IL-1 levels are found in the synovial fluid of patients with rheumatoid arthritis and osteoarthritis. In addition, IL-1 alpha may contribute to the pathogenesis of vascular occlusion and injury.

INTERLEUKIN-1 BETA(IL-1 BETA)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-1 beta (IL-1 beta) controls certain immune system reactions, including inflammation, swelling, fever, and shivering. IL-1 stimulates T-cells to secrete IL-2 and activate the inflammatory response. It also causes the hypothalamus to increase the body temperature. The two distinct forms of the protein, IL-1 alpha and IL-1 beta, perform the same functions but are structurally quite distinct. Biological effects of IL-1 include replacing macrophage requirements for T-cell activation, inducing fever and shivering, promoting prostaglandin production, promoting leukocyte growth, augmenting corticosteroid release, promoting hematopoesis, and promoting wound healing. Peripheral blood mononuclear cells of patients with aplastic anemia show markedly decreased IL-1 levels, although myelodysplastic patients with comparable degrees of pancytopenia have normal IL-1 production. Elevated IL-1 levels are found in the synovial fluid of patients with rheumatoid arthritis and osteoarthritis. Unlike IL-1 alpha, which is intracellular until cell death, IL-1 beta is secreted outside the cell.

INTERLEUKIN-2(IL-2)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-2 (IL-2) is important in anti-inflammatory reactions, blood cell production, and elimination of cancer cells at an early stage of cancer development. Its levels may be elevated in a number of inflammatory conditions as well as various forms of cancer. It stimulates the synthesis of interferon- gamma in peripheral leukocytes and induces the secretion of IL-1, tumor necrosis factor (TNF)-alpha and TNF-beta. IL-2 also supports the proliferation and clonal expansion of T-cells that specifically attack certain tumor cell types and is increasingly used to treat patients with cancers refractory to conventional treatment. A number of diseases have been found to be associated with the aberrant expression of IL-2 or IL-2 receptors, including Hodgkin’s disease, graft-versus-host disease, multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes, lepromatous leprosy, AIDS, immunodeficiency syndrome, severe burns, and allogeneic bone marrow transplantation.

INTERLEUKIN-3(IL-3)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-3 (IL-3) helps to stimulate the development and functioning of various types of blood cells. Its levels may be abnormal in a variety of inflammatory and blood cell diseases. IL-3 is produced mainly by T-cells (following cell activation by antigens and mitogens) but also by keratinocytes, natural killer cells, mast cells, endothelial cells, and monocytes. It is one of the priming factors for hematopoietic stem cells in vitro and in vivo, making these cells responsive to later-acting factors such as erythropoietin, granulocyte/ macrophage colony-stimulating factor, and IL-6. IL-3 also induces the increased expression of receptors for colony-stimulating factors, induces mast cell and macrophage proliferation, and stimulates histamine synthesis by mast cells and phagocytosis by macrophages. At picomolar-to-nanomolar concentrations, IL-3 chemoattracts eosinophils and influences the chemotactic behavior of these cells in response to other chemotactically active factors. At nanomolar concentrations, it induces the expression of complement factor C3a receptors in basophils.

INTERLEUKIN-4(IL-4)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-4 (IL-4) helps to control the immune system’s response to inflammation. Its levels may be abnormal in inflammatory conditions as well as autoimmune diseases. IL-4 is produced mainly by a subpopulation of activated T-cells (Th2), which are the most active of the helper cells for B-cells and which also secrete IL-5 and IL-6 alpha. IL-4 may be useful in the treatment of inflammatory conditions and autoimmune diseases since it inhibits the production of inflammatory cytokines such as IL-1, IL-6, and tumor necrosis factor. It may also be useful in the treatment of solid tumors, hematopoietic diseases, and immune defects; it inhibits the growth of colon and mammary carcinomas and augments the development of lymphokine- activated killer cells. IL-4 may play an essential role in the pathogenesis of chronic lymphocytic leukemia.

INTERLEUKIN-5(IL-5)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-5 (IL-5) is produced by T-cells (a type of white blood cell) and is specifically responsible for the growth and maturation of eosinophils (another type of white blood cell). Its levels may be abnormal in certain infectious and inflammatory disorders. IL-5 also promotes the generation of cytotoxic T-cells from thymocytes. A possible clinical application is suggested by its effect on eosinophils; animal experiments have shown that induced eosinophilia and lung infiltration by eosinophils in mice can be prevented by administration of monoclonal antibodies directed against IL-5.

INTERLEUKIN-6(IL-6)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Levels of interleukin-6 (IL-6) may be elevated in a variety of inflammatory and infectious diseases and other various stimuli. In addition to its role as an acute phase reactant and endogenous pyrogen, it is involved in B-cell differentiation into plasma cells. IL-6 is usually not detectable in serum, plasma, CSF, or joint fluid. Elevated levels are observed in a variety of inflammatory processes, including endotoxemia and collagen vascular diseases, as well as in alcoholic cirrhosis and chronic renal failure.

INTERLEUKIN-7(IL-7)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Levels of interleukin-7 (IL-7) may be elevated in a variety of inflammatory and infectious diseases. IL-7 stimulates the proliferation of pre-B- and pro-B-cells without affecting differentiation or mature B-cells. It also selectively supports the maturation of megakaryocytes and stimulates the proliferation of early and mature activated T-cells (synergized by suboptimal doses of IL-1). It stimulates the proliferation of thymocytes with certain CD markers and is therefore an important differentiation factor for functionally different T-lymphocyte subpopulations. In peripheral monocytes, IL-7 induces the synthesis of inflammatory mediators; in activated T-cells, it enhances the expression and secretion of IL-3 and granulocyte/macrophage colony- stimulating factor; and in macrophages, it down-regulates the expression of transforming growth factor (TGF)-beta.

INTERLEUKIN-8(IL-8)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-8 (IL-8) is involved in a variety of inflammatory processes and may be particularly important in psoriasis and rheumatoid arthritis. Elevated concentrations are observed in psoriatic scales, which may explain the high proliferation rate of these cells. IL-8 may also be a marker of inflammatory processes and probably plays a role in the pathogenesis of chronic polyarthritis since excessive amounts of IL-8 are found in synovial fluid.

INTERLEUKIN-10(IL-10)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-10 (IL-10) is involved in the elimination of cancer cells at an early stage of development and may suppress the growth of certain cancers, such as non-Hodgkin’s lymphoma. IL-10 is produced by, and down-regulates the function of, Th1 and Th2 cells. In macrophages stimulated by bacterial lipopolysaccharides, it inhibits the synthesis of IL-1, IL-6, and tumor necrosis factor-alpha by promoting the degradation of cytokine mRNA, and it also inhibits antigen presentation. In monocytes, interferon-gamma and IL-10 antagonize each other’s production and function. IL-10 has also been shown to be a physiologic antagonist of IL-12, and studies suggest that it indirectly suppresses the growth of certain tumors by inhibiting the infiltration of macrophages that may promote tumor growth. IL-10 has been detected in the sera of a subgroup of patients with active non-Hodgkin’s lymphoma, and levels appear to correlate with mortality in patients with intermediate or high- grade disease.

INTERLEUKIN-12 p40(IL-12 p40)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-12 (IL-12) is produced by white blood cells called lymphocytes and may help to prevent certain cancers. IL-12 levels may also be elevated in bacterial and parasitic infections. IL-12 p40 is the 40 kDa subunit of IL-12, which is secreted by peripheral lymphocytes (mainly B-cells and to a lesser extent T-cells) after induction. IL-12 may be useful in expanding an antigen- specific T-cell population and has been shown to augment natural killer cell- mediated cytotoxicity in a number of conditions, including hairy cell leukemia. Its abilities to induce the synthesis of interferon (IFN)-gamma and to stimulate the proliferation of resting peripheral cells may also be important. In vivo, IL-12 inhibits the growth of a variety of experimental tumors and has antiangiogenic effects that are at least partly mediated by IFN-gamma. Therefore, IL-12 seems to be a potential candidate in the treatment of angiogenesis-dependent malignancies.

INTERLEUKIN-12 p70(IL-12 p70)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-12 (IL-12) is produced by white blood cells called lymphocytes and may help to prevent certain cancers. IL-12 levels may also be elevated in bacterial and parasitic infections. IL-12 p70 is the 70 kDa subunit of IL-12, which is secreted by peripheral lymphocytes (mainly B-cells and to a lesser extent T-cells) after induction. IL-12 may be useful in expanding an antigen- specific T-cell population and has been shown to augment natural killer cell- mediated cytotoxicity in a number of conditions, including hairy cell leukemia. Its abilities to induce the synthesis of interferon (IFN)-gamma and to stimulate the proliferation of resting peripheral cells may also be important. In vivo, IL-12 inhibits the growth of a variety of experimental tumors and has antiangiogenic effects that are at least partly mediated by IFN-gamma. IL-12 therefore seems to be a potential candidate in the treatment of angiogenesis-dependent malignancies.

INTERLEUKIN-13(IL-13)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-13 (IL-13) controls the activity of white blood cells called macrophages and reduces the production of other cell signaling proteins, including some of the other interleukins. IL-13 is expressed in activated T-helper cells and T-cells expressing CD8. It down-modulates macrophage activity, reducing the production of pro-inflammatory cytokines (IL-1, IL-6, IL-8, IL-10, and IL-12) and chemokines (MIP-1 and MCP) in response to interferon-gamma or bacterial lipopolysaccharides. IL-13 also enhances the production of the IL-1 receptor antagonist and decreases the production of nitric oxide by activated macrophages, leading to a decrease in parasiticidal activity.

INTERLEUKIN-15(IL-15)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-15 (IL-15) controls the activity of white blood cells called macrophages and reduces the production of other cell signaling proteins, including some of the other interleukins. Some of the biological activities of IL-15 resemble those of IL-2, but IL-15 and IL-2 differ in their controls of expression and secretion, their range of target cells, and their functional activities. IL-15 stimulates proliferation of the established T-cell line CTLL-2 as well as phytohemagglutinin-stimulated peripheral blood mononuclear cells. In addition, IL-15 can induce generation of cytolytic cells and lymphokine-activated killer cells activity in vitro. IL-15 appears to function as a specific maturation factor for natural killer (NK) cells and can mimic the bone marrow microenvironment in vitro, which is required for NK cells to acquire lytic functions. IL-15 inhibits apoptosis induced by deprivation of cytokines in activated T-cells and inhibits apoptosis induced by various antibodies in a manner dependent on RNA synthesis.

INTERLEUKIN-16(IL-16)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-16 (IL-16) attracts certain white blood cells, including T-cell lymphocytes, macrophages, and eosinophils. IL-16 was originally described as lymphocyte chemoattractant factor (LCF), which chemoattracts CD4+ T-cells, macrophages, and eosinophils. It is secreted by activated CD8+ cells. Very high levels of IL-16 are produced in response to IL-1 beta.

INTERLEUKIN-18(IL-18)


Interleukins are cytokine (cell signaling) proteins produced by white blood cells, which help to control immune system and inflammation responses. Interleukin-18 (IL-18) helps to control the activity of some of the white blood cells involved in the immune response. Increased levels of IL-18 may be associated with Crohn’s disease. IL-18 is one of the pro-inflammatory cytokines. One important function is the regulation of functionally distinct subsets of T-helper cells required for cell-mediated immune responses. Abnormal expression of IL-18 has been observed in autoimmune non-obese diabetic (NOD) mice and appears to be closely associated with the development of diabetes.

IRON BINDING CAPACITY, TOTAL(TIBC)


Iron in blood is carried by the transport protein, transferrin. Total iron binding capacity measures your body’s ability to transport iron and is usually higher than normal when the body’s iron stores are low. An increased iron binding capacity (TIBC) is seen in iron deficiency states, which are often related to blood loss or anemia. In iron overload states, such as hemochromatosis, iron levels are high and TIBC is low or normal. In liver disease, TIBC and transferrin levels are low, since transferrin is made in the liver. Because transferrin levels fall relatively rapidly when there is insufficient protein in the diet, TIBC can also be used to monitor nutrition. A decreased TIBC is often seen in chronic inflammatory disorders, kwashiorkor, chronic iron overloading, and malignancies.

IRON BINDING CAPACITY, UNSATURATED(UIBC)


Unsaturated iron binding capacity (UIBC) is the reserve iron binding capacity of serum. Iron in blood is carried by the transport protein, transferrin. Only about one-third of the iron binding sites of transferrin are normally occupied by Fe (III); therefore, serum has considerable reserve iron binding capacity. UIBC levels may be used to detect hereditary hemochromatosis, or iron overload.

IRON, PERCENT SATURATED


Saturated iron binding capacity is a measure of the percentage of transferrin and other mobile, iron-binding proteins saturated with iron.

IRON, SERUM


Iron is an important mineral that is involved in the transport of oxygen in the blood. About 65% of the body’s iron are attached to hemoglobin. Iron deficiency anemia is the most common nutritional disorder in the world and is found primarily among young children and premenopausal women. Measurement of iron in serum aids in the evaluation of a number of conditions involving erythrocyte production and destruction, iron metabolism, iron transport, or nutrition. Elevated serum levels of iron may occur in hemochromatosis, hemolysis, hemolytic anemia, hemosiderosis, hepatic necrosis, hepatitis, vitamin B12 deficiency, and lead toxicity. Decreased serum iron levels may occur in iron deficiency anemia, malabsorption, nephrotic syndrome, insufficient dietary iron, and circumstances involving chronic or heavy bleeding.

JO-1 ANTIBODY


The presence of antibodies against the Jo-1 antigen occurs in various autoimmune inflammatory conditions, including myositis, interstitial lung disease, and arthritis conditions. Antibodies against the Jo-1 antigen (histidyl-tRNA synthetase) are found in about 30% of adult patients with myositis and are particularly common (about 60%) in patients with both myositis and interstitial lung disease (cryptogenic fibrosing alveolitis or pulmonary interstitial fibrosis). Jo-1 antibodies are most often found in patients with the anti-synthetase syndrome, which is characterized by an acute onset, steroid-responsive myositis with interstitial lung disease, fever, symmetrical arthritis, Raynaud’s phenomenon, and “mechanic’s hands.”

LACTATE DEHYDROGENASE(LDH)


Many different types of body cells contain the enzyme lactate dehydrogenase, particularly those in the heart, kidney, liver, and muscle. LDH levels may be abnormally high in heart attack and liver disease, as well as other diseases. LDH catalyzes the conversion of lactate to pyruvate, an important step in energy production in cells. LDH levels are used for assessment of myocardial infarction, liver disease, pernicious and megaloblastic anemia, pulmonary embolus, malignancy, and muscular dystrophy.

LEISHMANIA DONOVANI ANTIBODY(L. DONOVANI Ab)


Leishmania donovani is an infectious parasite that causes visceral leishmaniasis, including kala-azar, also known as black fever. Leishmania parasites are transmitted by the bite of female Phlebotominae sandflies. It is rarely found in the U.S. but has been reported in the states bordering Mexico.

LEPTIN


Leptin is a protein hormone, expressed primarily by fat cells, which helps to control body weight through effects on appetite centers in the brain. Typically, obese individuals have higher leptin levels. Leptin is also produced by epithelial cells in the stomach and placenta. Leptin acts on a receptor site in the ventromedial nucleus of the hypothalamus to curb appetite and increase energy expenditure as body fat stores increase. Leptin levels are 40% higher in women than in men and show a further 50% rise just before menarche, later returning to baseline levels. Serum leptin levels are lowered by fasting and increased by inflammation, and increased leptin levels are seen in obese individuals. Although mutations in both the leptin and leptin receptor genes have been found in a small number of morbidly obese human subjects with abnormal eating behavior, the majority of obese people do not show such mutations and have normal or elevated circulating leptin levels.

LIPOPROTEIN(a) [(Lp(a)]


Lipoprotein (a) [(Lp(a)] blood levels are mostly determined by inherited genes, with a heritability of about 90%. Elevated levels of LP(a) are associated with an increased risk of coronary heart disease. Lp(a) is an atherogenic plasma protein whose structure resembles that of low-density lipoprotein (LDL). Lp(a) appears to competitively inhibit plasminogen activation, thus interfering with fibrinolysis and increasing thrombogenic risk. Increased Lp(a) levels are associated with rapid progression of coronary disease and an increased risk of clinical recurrence after angioplasty.

LOW-DENSITY LIPOPROTEIN(LDL)


Cholesterol carried by low-density lipoprotein (LDL) is known as the “bad cholesterol” because higher levels of LDL-cholesterol are associated with an increased risk for coronary heart disease. LDL oxidation promotes foam cell formation (the origin of atherosclerosis) and impairs endothelial cell function. Reduction of LDL-cholesterol levels is associated with atherosclerotic regression or lack of progression on angiographic studies.

LOW-DENSITY LIPOPROTEIN/HIGH-DENSITY LIPOPROTEIN RATIO(LDL/HDL RATIO)


The low-density lipoprotein/high-density lipoprotein (LDL/HDL) ratio is the ratio of “bad cholesterol” to “good cholesterol” and is used because a high level of HDL may partially offset the negative effects of a high LDL level. A ratio of 3 represents an average risk level, while people with ratios of 2.5 or less have only half the risk of heart disease as does the population at large. Evaluation of cardiac risk requires information about total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, and ratios of LDL-cholesterol or total cholesterol to HDL-cholesterol.

LUTEINIZING HORMONE(LH)


Luteinizing hormone (LH) is a hormone released by the pituitary gland. In women, a surge of LH in the middle of the menstrual cycle first causes ovulation, then stimulates the ovaries to produce estrogen and progesterone for about a week. In men, LH stimulates the production of androgen (a male hormone) by the testes. LH is typically increased in menopausal women, women with poorly functioning ovaries, and men with poorly functioning testes. LH is synthesized in the anterior lobe of the hypophysis, and activation and secretion are controlled by gonadotropin-releasing hormone from the hypothalamus. In females, LH stimulates the ovarian theca cells to synthesize and secrete steroid hormones. It induces ovulation of the ripe follicle and formation of the corpus luteum, then remains dominant in the luteal phase in order to maintain the corpus luteum and endometrium in the event of pregnancy. In males, LH stimulates the Leydig cells to secrete testosterone. Increased levels of LH are associated with menopause, primary ovarian hypofunction, and polycystic ovarian syndrome in females, and primary hypogonadism in males. Decreased LH levels are associated with secondary and tertiary ovarian hypofunction in females and secondary hypogonadism in males.

LYME DISEASE ANTIBODY(BORRELIA BURGDORFERI ANTIBODY, B. BURGDORFERI Ab)


Borrelia burgdorferi is the bacterium that causes Lyme disease. This disease may cause many different signs and symptoms including rash, arthritis, central nervous system problems, and heart-related ailments. The presence of the antibody against Borrelia burgdorferi indicates prior or current exposure to or infection with this bacterium. Transmission of the spirochete Borrelia burgdorferi is via the bite of an infected tick of the Ixodid species. Lyme borreliosis is the most common vector-borne disease in the United States. In the majority of cases, it is easily treated and does not progress to the chronic stage; severe, long-term effects probably occur in fewer than 10% of untreated patients.

LYMPHOCYTE COUNT


Lymphocytes make up 20% to 40% of all white blood cells in the bloodstream and are part of the body’s immune system. They identify foreign substances, bacteria, and viruses in the body and produce antibodies against them. Patients with lymphocyte deficiencies may be more vulnerable to infections. Occasionally, those with an excessive number of lymphocytes are found to have a type of leukemia. Lymphocytes are produced in the bone marrow. The lymphocyte count is normally >1,000 cells/μl of blood in adults and >3,000 cells/μl in children. A variety of diseases and conditions, including HIV infection, can decrease lymphocyte numbers, although reduced numbers may not significantly decrease the total white blood cell count. Lymphocyte numbers may also fall briefly during times of severe stress and while using corticosteroids or undergoing cancer chemotherapy or radiation therapy. A severe reduction may occur in certain hereditary disorders. Insufficient B-cell numbers can lead to reduced antibody production, while insufficient T-cells or natural killer cells can cause patients to have problems overcoming certain infections, especially those caused by viruses, fungi, and parasites.

LYMPHOCYTE PERCENTAGE


Lymphocytes make up 20% to 40% of all white blood cells in the bloodstream and are part of the body’s immune system. They identify foreign substances, bacteria, and viruses in the body and produce antibodies against them. Patients with lymphocyte deficiencies may be more vulnerable to infections. Occasionally, those with an excessive number of lymphocytes are found to have a type of leukemia. Lymphocytes are produced in the bone marrow. The lymphocyte count is normally >1,000 cells/μl of blood in adults and >3,000 cells/μl in children. A variety of diseases and conditions, including HIV infection, can decrease lymphocyte numbers, although reduced numbers may not significantly decrease the total white blood cell count. Lymphocyte numbers may also fall briefly during times of severe stress and while using corticosteroids or undergoing cancer chemotherapy or radiation therapy. A severe reduction may occur in certain hereditary disorders. Insufficient B-cell numbers can lead to reduced antibody production, while insufficient T-cells or natural killer cells can cause patients to have problems overcoming certain infections, especially those caused by viruses, fungi, and parasites.

LYMPHOTACTIN


Lymphotactin is a protein that chemically attracts the white blood cells called lymphocytes. Lymphotactin is produced by activated progenitor T-cells and is characterized by specific chemotactic activity for lymphocytes, but not for monocytes or neutrophils, a characteristic that makes it unique among chemokines. Lymphotactin is produced by natural killer (NK) cells and attracts both NK cells and T-cells in vivo but does not affect the adhesiveness of NK cells to vascular endothelium. It also has the ability to inhibit immature subsets of myeloid progenitors stimulated to proliferate by multiple growth factors.

MACROPHAGE-DERIVED CHEMOKINE(MDC)


Macrophage-derived chemokine (MDC) is made by macrophages and powerfully attracts white blood cells called neutrophils. High levels of MDC are seen in macrophages associated with atherosclerotic plaques, the buildups that occur in blood vessels affected by coronary heart disease. MDC is highly expressed in macrophages and monocyte-derived dendritic cells, but not in monocytes, natural killer cells, or several cell lines of epithelial, endothelial, or fibroblast origin. High MDC expression occurs in the normal thymus and less in lung and spleen. MDC is expressed by a subset of macrophages within regions of advanced atherosclerotic plaques that contain plaque microvessels. MDC is also a potent chemoattractant for neutrophilic granulocytes, enhances these cells’ bactericidal activity, and stimulates the release of lysozyme.

MACROPHAGE INFLAMMATORY PROTEIN 1 ALPHA(MIP-1 ALPHA)


Macrophage inflammatory proteins are produced by white blood cells called macrophages after stimulation from bacteria. These proteins stimulate the activity of other white blood cells (called neutrophils, eosinophils, and basophils) in response to infection or inflammation. The two macrophage inflammatory proteins (MIP-1 alpha and MIP-1 beta) are the major factors produced by macrophages stimulated with bacterial endotoxins. Both are involved in the activation of granulocytes and appear to be involved in acute neutrophilic inflammation. Both also stimulate the production of reactive oxygen species in neutrophils, stimulate the release of lysosomal enzymes, and induce the synthesis of other pro-inflammatory cytokines in fibroblasts and macrophages. MIP-1 alpha is a potent basophil agonist, inducing a rapid change of cytosolic free calcium and the release of histamine and sulfidoleukotrienes.

MACROPHAGE INFLAMMATORY PROTEIN 1 BETA(MIP-1 BETA)


Macrophage inflammatory proteins are produced by white blood cells called macrophages after stimulation from bacteria. These proteins stimulate the activity of other white blood cells (called neutrophils, eosinophils, and basophils) in response to infection or inflammation. The two macrophage inflammatory proteins (MIP-1 alpha and MIP-1 beta) are the major factors produced by macrophages stimulated with bacterial endotoxins. Both are involved in the activation of granulocytes and appear to be involved in acute neutrophilic inflammation. Both also stimulate the production of reactive oxygen species in neutrophils, stimulate the release of lysosomal enzymes, and induce the synthesis of other pro-inflammatory cytokines in fibroblasts and macrophages.

MAGNESIUM(Mg)


Magnesium (Mg) is a mineral involved in many bodily processes, including nerve signaling, the building of healthy bones, and muscle contraction. It is important in the normal functioning of more than 300 enzymes in the body. Low blood levels of magnesium may result from a number of conditions including chronic diarrhea, chronic vomiting, hyperaldosteronism, celiac disease, and others. Magnesium is a cofactor for more than 300 human enzymes. It is an activator of many enzyme systems and is important in oxidative phosphorylation, glycolysis, cell replication, nucleotide metabolism, and protein biosynthesis. Because magnesium inhibits the entry of calcium into neurons, low magnesium levels result in increased neuromuscular excitability. Hypermagnesemia may result from renal failure, adrenal insufficiency, hypothyroidism, tissue breakdown, or the overuse of antacids or laxatives. Hypomagnesemia may result from malabsorption, starvation, severe diarrhea, chronic vomiting, celiac sprue, chronic renal failure with wasting, renal tubular acidosis, acute pancreatitis, hyperthyroidism, hyperparathyroidism, diabetes mellitus, hyperaldosteronism, and the use of certain medications.

MATRIX METALLOPROTEINASE 2(MMP-2)


Matrix metalloproteinases, such as MMP-2 (also called gelatinase A), are enzymes that break down the structural proteins that hold tissues together. The blood levels of several of these enzymes may be elevated during normal wound healing, pregnancy, and the creation of new blood vessels, but these levels may also be elevated in various diseases involving tissue destruction and/or inflammation, including various cancers, periodontitis, rheumatoid arthritis, osteoarthritis, ulcerated wounds, and certain autoimmune diseases. Under physiologic conditions, MMPs are involved in extracellular degradation and breakdown of matrix proteins during normal tissue remodeling processes such as wound healing, pregnancy, and angiogenesis. However, the release of these enzymes by various cell types has also been implicated in the pathogenesis of many diseases, including periodontitis, rheumatoid arthritis, osteoarthritis, glomerulonephritis, chronic ulcerations, uterine involution, autoimmune disorders of skin and dermal photoaging, and tumor progression and metastasis. It has been suggested that tissue destruction in disease processes often correlates with an imbalance of MMPs over their protein inhibitors, tissue inhibitors of MMPs (TIMPs).

MATRIX METALLOPROTEINASE 3(MMP-3)


Matrix metalloproteinases (MMPs) are enzymes that break down the structural proteins that hold tissues together. The blood levels of several of these enzymes may be elevated during normal wound healing, pregnancy, and the creation of new blood vessels, but these levels may also be elevated in various diseases involving tissue destruction and/or inflammation, including various cancers, periodontitis, rheumatoid arthritis, osteoarthritis, ulcerated wounds, and certain autoimmune diseases. Under physiologic conditions, MMPs are involved in extracellular degradation and breakdown of matrix proteins during normal tissue remodeling processes such as wound healing, pregnancy, and angiogenesis. However, the release of these enzymes by various cell types has also been implicated in the pathogenesis of many diseases, including periodontitis, rheumatoid arthritis, osteoarthritis, glomerulonephritis, chronic ulcerations, uterine involution, autoimmune disorders of skin and dermal photoaging, and tumor progression and metastasis. It has been suggested that tissue destruction in disease processes often correlates with an imbalance of MMPs over their protein inhibitors, tissue inhibitors of MMPs (TIMPs). Levels of MMP-3 (also termed stromelysin-1, transin-1, proteoglycanase, and pro-collagenase activating protein) have been found to be elevated in a number of unrelated diseases, including meningococcal meningitis, chronic transplant nephropathy, coronary aneurysms, rheumatoid arthritis (especially in the presence of cartilage damage), psoriatic arthritis, systemic lupus erythematosus, and mixed connective tissue disease.

MATRIX METALLOPROTEINASE 9(MMP-9)


Matrix metalloproteinases (MMPs) are enzymes that break down the structural proteins that hold tissues together. The blood levels of several of these enzymes may be elevated during normal wound healing, pregnancy, and the creation of new blood vessels, but these levels may also be elevated in various diseases involving tissue destruction and/or inflammation, including various cancers, periodontitis, rheumatoid arthritis, osteoarthritis, ulcerated wounds, and certain autoimmune diseases. Under physiologic conditions, MMPs are involved in extracellular degradation and breakdown of matrix proteins during normal tissue remodeling processes such as wound healing, pregnancy, and angiogenesis. However, the release of these enzymes by various cell types has also been implicated in the pathogenesis of many diseases, including periodontitis, rheumatoid arthritis, osteoarthritis, glomerulonephritis, chronic ulcerations, uterine involution, autoimmune disorders of skin and dermal photoaging, and tumor progression and metastasis. It has been suggested that tissue destruction in disease processes often correlates with an imbalance of MMPs over their protein inhibitors, tissue inhibitors of MMPs (TIMPs). MMP-9 (also known as gelatinase B) is often expressed by human cancer cells. Elevated plasma levels have been observed in patients with abdominal aortic aneurysm and giant cell arteritis, and elevated CSF levels in patients with multiple sclerosis.

MEAN CORPUSCULAR HEMOGLOBIN(MCH)


Mean corpuscular hemoglobin (MCH) is an estimate of the amount of hemoglobin carried by each red blood cell. Hemoglobin is the iron-binding protein that carries oxygen. MCH may be low due to blood loss or anemia. An abnormally elevated MCH (over 34%) may result from macrocytic anemia, while an abnormally low MCH (below 26%) may occur due to blood loss over time, too little iron in the body, microcytic anemia, or hemoglobinopathies.

MEAN CORPUSCULAR HEMOGLOBIN CONCENTRATION(MCHC)


Mean corpuscular hemoglobin concentration (MCHC) is an estimate of the level of hemoglobin (the iron-binding protein that carries oxygen) in a given number of packed and transfusable red blood cells. An abnormally elevated MCHC (over 36%) may be due to spherocytosis, unstable hemoglobin, or vitamin B12 or folic acid deficiency. An abnormally low MCHC (below 28%) may be due to blood loss over time, iron deficiency, or hypochromic anemia.

MEAN CORPUSCULAR VOLUME(MCV)


Mean corpuscular volume is the average amount of space occupied by each red blood cell. Causes of a high MCV include liver disease, alcohol abuse, hypothyroidism, reticulocytosis, marrow aplasia, vitamin B12 or folic acid deficiency, and myelofibrosis. Causes of a low MCV include iron deficiency anemia, lead poisoning, chronic kidney failure, hemoglobinopathy, and certain other anemias.

MITOCHONDRIAL ANTIBODY


Mitochondria are the parts of our cells that produce energy. Antibodies against mitochondria are produced in some autoimmune conditions. The detection of mitochondrial antibodies is useful in the evaluation of a number of conditions. Various subtypes of these antibodies have been associated with primary biliary cirrhosis, syphilis, pseudosyphilis, and isoniazid-induced hepatitis. A titer of above 50 IU/ml of M2 mitochondrial antibodies suggests primary biliary cirrhosis even in the absence of symptoms and the presence of normal alkaline phosphatase levels.

MONOCYTE CHEMOTACTIC PROTEIN-1(MCP-1)


Monocyte chemotactic protein-1 (MCP-1) is a cell signaling protein produced by the body in response to inflammation. It attracts white blood cells to the inflamed area to combat disease-causing organisms (such as bacteria or viruses). MCP-1 levels are elevated in a variety of infections and inflammatory processes. Monocyte chemotactic protein-1 (also called small inducible cytokine A2 and monocyte chemotactic and activating factor) plays a role in the recruitment of monocytes to sites of injury and infection. It has been found in the joints of rheumatoid arthritis patients, where it may recruit macrophages and perpetuate joint inflammation. Elevated levels of MCP-1 have also been found in the urine of systemic lupus erythematosus patients as a sign of renal inflammation.

MONOCYTE COUNT


Monocytes are a type of white blood cell involved in the immune response to foreign substances. The monocyte number is often increased in response to chronic infections, inflammatory bowel disease, leukemia, and certain cancers. It may be decreased in people who have anemia or are taking corticosteroids. Monocytes help to remove necrotic tissues and account for 2% to 8% of circulating leukocytes. After a few hours in the bloodstream, they migrate into tissues and mature into macrophages. An increased monocyte number (monocytosis) occurs in response to viral or parasitic infection, inflammatory bowel disease, sarcoidosis, monocytic leukemia, lymphoma, multiple myeloma, and certain neoplasms. A low monocyte number (monocytopenia) can occur in aplastic or lymphocytic anemia and in patients receiving corticosteroids.

MONOCYTE PERCENTAGE


Monocytes are a type of white blood cell involved in the immune response to foreign substances. The monocyte number is often increased in response to chronic infections, inflammatory bowel disease, leukemia, and certain cancers. It may be decreased in people who have anemia or are taking corticosteroids. Monocytes help to remove necrotic tissues and account for 2% to 8% of circulating leukocytes. After a few hours in the bloodstream, they migrate into tissues and mature into macrophages. An increased monocyte number (monocytosis) occurs in response to viral or parasitic infection, inflammatory bowel disease, sarcoidosis, monocytic leukemia, lymphoma, multiple myeloma, and certain neoplasms. A low monocyte number (monocytopenia) can occur in aplastic or lymphocytic anemia and in patients receiving corticosteroids.

MUMPS ANTIBODY


Antibodies against the paramyxovirus that causes mumps indicate either prior exposure or vaccination. Children with type 1 diabetes mellitus tend to have unusually low IgG mumps virus antibody levels.

MYCOBACTERIA TUBERCULOSIS ANTIBODY(M. TUBERCULOSIS Ab)


Mycobacteria tuberculosis is the bacterium that causes tuberculosis (TB). The presence of antibodies against this bacterium indicates recent exposure to or infection with it. Ninety percent of those infected have asymptomatic latent TB infection, with a 10% lifetime risk of progression to active disease. Tuberculosis is the most common major infectious disease in the world, with about 2 billion people infected. The World Health Organization declared tuberculosis to be a global health emergency in 1993.

MYCOPLASMA PNEUMONIAE ANTIBODY(M. PNEUMONIAE Ab)


Mycoplasma pneumoniae is a bacterium that causes respiratory infections, including pneumonia. The presence of antibodies to Mycoplasma pneumoniae indicates recent exposure to or infection with these bacteria. Mycoplasma pneumoniae is the causative organism in 15% to 20% of pneumonia cases but can also cause asymptomatic respiratory infections, acute tracheobronchitis, or Stevens-Johnson syndrome. Levels of IgG and IgM antibodies vary according to time after the onset of illness and patient age; adults tend to have higher IgG antibody levels than do children.

MYELOPEROXIDASE ANTIBODY(MPO Ab)


Myeloperoxidase (MPO) is an enzyme primarily found in neutrophils (a type of white blood cell). Antibodies against this enzyme appear to play a role in the development of certain kidney and blood vessel diseases. Antibodies against MPO are a subclass of anti-neutrophil cytoplasmic antibodies (ANCAs). They are associated with various disorders, including Churg-Strauss syndrome, crescentic glomerulonephritis, microscopic polyangiitis, polyarteritis nodosa, Wegener’s granulomatosis, and possibly lupus nephritis, Henoch-Schonlein purpura, and giant cell arteritis.

MYOGLOBIN


Myoglobin is the primary oxygen-carrying protein in muscle tissues. Its presence in the blood indicates muscle injury, either to skeletal muscles or to the heart muscle during a heart attack. When muscles are severely damaged by injury or disease, the release of myoglobin may cause kidney damage. Myoglobin is a monomeric heme protein that is structurally related to hemoglobin and found predominantly in skeletal and cardiac muscle. During the course of a myocardial infarction, myoglobin is released from the ischemic myocardium. Elevated levels may be detected as early as 30 minutes after chest pain begins and generally peak after 6 to 12 hours and return to baseline within 24 to 36 hours. Skeletal muscles can be damaged by a wide variety of pathological processes, causing release of myoglobin into the circulation (rhabdomyolysis) and myoglobinuria. In rhabdomyolysis, a high serum myoglobin level, especially with a low urine myoglobin clearance rate, indicates a high risk for renal failure due to the damage done to the kidneys by myoglobin and its metabolites.

NEUTROPHIL COUNT


Neutrophils are a type of white blood cell whose numbers are elevated in the presence of bacterial and other infections, tissue injury and inflammation, stress, certain metabolic conditions, myeloproliferative disorders, metastatic cancer, and some medications. The neutrophil number is decreased in cases of depressed neutrophil production, such as leukemia or aplastic anemia, and in cases of neutrophil destruction, such as sepsis or systemic lupus erythematosus.

NEUTROPHIL PERCENTAGE


Neutrophils are a type of white blood cell involved in the immune response to infection, primarily bacterial infection. The neutrophil percentage is often increased in the presence of bacterial infection and other conditions such as tissue injury, stress, inflammation, and certain metabolic conditions. The neutrophil percentage may be decreased in conditions that suppress production or increase destruction.

PANCREATIC ISLET CELL ANTIBODY


Type 1 (“juvenile”) diabetes mellitus is most likely an autoimmune disease in which the body’s own antibodies have destroyed the insulin-producing islet cells of the pancreas. This produces a deficiency of insulin, which normally regulates glucose levels in the blood. Autoantibodies against various pancreatic islet cell antigens are present in more than 80% of type 1 diabetes patients and predict the development of this disease, particularly if high, persistent titers are present and the patient is young. The seroprevalence of these antibodies in healthy children is about 4%, corresponding to the prevalence of type 1 diabetes. Islet cell antibodies are also present in some patients with autoimmune disorders or schistosomiasis.

PARAINFLUENZA TYPE 1 ANTIBODY


Parainfluenza viruses typically cause respiratory infections. The presence of antibodies against a parainfluenza virus indicates recent exposure or infection. Parainfluenza viruses are categorized into types 1, 2, 3, and 4, of which types 1, 2, and 3 are most common. Types 1 and 2 can cause epidemic laryngotracheobronchitis (croup) and sometimes colds, pharyngitis, and tracheobronchitis in children during the fall. Localized outbreaks may occur in nurseries, schools, pediatric wards, and similar settings. Reinfection generally causes mild upper respiratory illnesses and may be asymptomatic in adults.

PARAINFLUENZA TYPE 2 ANTIBODY


Parainfluenza viruses typically cause respiratory infections. The presence of antibodies against a parainfluenza virus indicates recent exposure or infection. Parainfluenza viruses are categorized into types 1, 2, 3, and 4, of which types 1, 2, and 3 are most common. Types 1 and 2 can cause epidemic laryngotracheobronchitis (croup) and sometimes colds, pharyngitis, and tracheobronchitis in children during the fall. Localized outbreaks may occur in nurseries, schools, pediatric wards, and similar settings. Reinfection generally causes mild upper respiratory illnesses and may be asymptomatic in adults.

PARAINFLUENZA TYPE 3 ANTIBODY


Parainfluenza viruses typically cause respiratory infections. The presence of antibodies against a parainfluenza virus indicates recent exposure or infection. Parainfluenza viruses are categorized into types 1, 2, 3, and 4, of which types 1, 2, and 3 are most common. Types 1 and 2 can cause epidemic laryngotracheobronchitis (croup) and sometimes colds, pharyngitis, and tracheobronchitis in children during the fall. Localized outbreaks may occur in nurseries, schools, pediatric wards, and similar settings. Reinfection generally causes mild upper respiratory illnesses and may be asymptomatic in adults.

PARATHYROID HORMONE(PTH)


Parathyroid hormone (PTH) is made in the parathyroid tissues near the thyroid gland in the neck. Levels of this hormone tightly control the level of calcium in the body. PTH levels may be abnormal in several kidney and metabolic disorders. Parathyroid hormone is a major regulator of the extracellular calcium concentration. It increases extracellular calcium by increasing calcium reabsorption in the kidneys and stimulating the release of calcium from skeletal calcium stores. Rising levels of extracellular calcium normally suppress PTH production through a negative feedback mechanism. High PTH levels may be associated with renal failure, hypomagnesemia, and gastrointestinal malabsorption, while low levels may occur in adrenal insufficiency, hyperthyroidism, and parathyroid malignancies.

PHOSPHORUS(P)


Phosphorus (P) is a basic element that is found throughout the body. Most of the body’s phosphorus is bound to calcium in the bones, but about 15% exist in the blood and other soft tissues and body fluids. Phosphorus is very important in metabolism. More than 80% of the body’s phosphorus exist as calcium phosphate in the skeleton; the remainder is a component of phospholipids, nucleic acids, and ATP. Nearly all serum phosphorus is present as inorganic phosphate, levels of which are controlled by parathyroid hormone, vitamin D, and calcitonin. Hyperphosphatemia has been observed in bone metastasis, hypocalcemia, hypoparathyroidism, liver disease, sarcoidosis, Addison’s disease, hypervitaminosis D, magnesium deficiency, myelogenous leukemia, and renal failure. Hypophosphatemia may occur in rickets, osteomalacia, diabetic ketoacidosis, hyperparathyroidism, hyperinsulinism, hypercalcemia, vitamin D deficiency, Gram-negative sepsis, and alcoholism, and in patients taking diuretics, corticosteroids, or aluminum hydroxide antacids.

PLASMINOGEN ACTIVATOR INHIBITOR TYPE 1(PAI-1)


Plasminogen activator inhibitor type 1 (PAI-1) blocks the activity of tissue plasminogen activator, which is the key enzyme involved in the breakdown of blood clots. Elevated levels of PAI-1 are associated with increased clotting and an increased risk of heart attack. Plasminogen activator inhibitor type 1 is an inhibitor of tissue plasminogen activator (tPA), a key enzyme in fibrinolysis. PAI-1 is synthesized by endothelial cells, activated platelets, and hepatocytes. As PAI-1 levels increase, active levels of tPA decrease, causing impaired fibrinolytic function. Elevated levels of PAI-1 have been observed in patients with deep vein thrombosis and myocardial infarction, as well as in normal pregnancy and sepsis.

PLATELET COUNT


Platelets are cellular elements involved in the blood clotting process. When a blood vessel is damaged, platelets clump together and help to initiate clotting. Abnormal platelet levels are found in a variety of blood-related and autoimmune diseases. Platelets are necessary for normal hemostasis, both because they aggregate to form clots and because they activate Factor VIII and release phospholipids necessary for coagulation. Potential causes of thrombocytopenia include various drugs, radiation, disseminated intravascular coagulation, aplastic or hemolytic anemia, hemolytic uremic syndrome, idiopathic thrombocytopenic purpura, leukemia, lymphoma, vasculitis, systemic lupus erythematosus, HIV, cytomegalovirus, sepsis, prosthetic heart valves, and massive blood transfusions. Thrombocytosis may be associated with polycythemia vera, post-splenectomy syndrome, inflammatory bowel disease, alcohol abuse, pancreatitis, cirrhosis, hemophilia, myelofibrosis, certain drugs, certain malignancies, and chronic myelogenous leukemia.

PM-1 ANTIBODY


Polymyositis is an autoimmune inflammatory disease of the connective tissues. The presence of Pm1 antibodies strongly suggests polymyositis, although levels of this antibody may also be elevated in other autoimmune diseases. About 60% of patients with myositis (primary idiopathic polymyositis, childhood polymyositis or dermatomyositis, primary idiopathic dermatomyositis in adults, inclusion body myositis, polymyositis or dermatomyositis associated with malignant tumors, or polymyositis or dermatomyositis associated with various connective tissue disease overlap syndromes) have antibodies to either Pm1 or Jo-1, although the relationship between these autoantibodies and the disease process remains unclear. Myositis may appear at any age but occurs most commonly between ages 5 and 15 and between ages 40 and 60.

POLIO ANTIBODY


The polio antibody test determines whether an individual has been recently vaccinated against or infected with the virus that causes polio. Polio is an epidemic infection that affects the brain and spinal cord. It has been eliminated in much of the world through universal vaccination.

POTASSIUM(K)


Potassium (K) is a positively charged electrolyte whose levels are tightly controlled throughout the body. Potassium plays an important role in the electrical conduction of signals in nerve, muscle, and heart tissues. A variety of hormonal, metabolic, and kidney conditions can cause abnormal potassium levels. Potassium is particularly important for maintaining the electric charge on the cell membrane. Potassium levels are mainly controlled by aldosterone. Causes of hyperkalemia include hypoaldosteronism, diabetes mellitus, interstitial nephritis, renal insufficiency, congestive heart failure, acidosis, dialysis, coronary bypass, gastrointestinal bleeding, and the use of heparin, potassium-sparing diuretics, succinylcholine, beta-blockers, high- dose penicillin, digitalis, arginine, or NSAIDs. Causes of hypokalemia include renal potassium loss, vomiting, chronic diarrhea, acute leukemia, metabolic acidosis or alkalosis, delirium tremens, and the use of beta-agonists, insulin excess, aminoglycosides, or high-dose penicillin. Abnormal potassium levels can lead to cardiac arrest.

PREGNANCY-ASSOCIATED PLASMA PROTEIN A(PAPP-A)


Pregnancy-associated plasma protein A (PAPP-A) is an enzyme first identified in the blood of pregnant women. Unusually low blood levels of PAPP-A during the first trimester of pregnancy indicate an increased risk of premature delivery, stillbirth, or other problems with the pregnancy. PAPP-A levels can also predict the likelihood of a heart attack or death in patients experiencing acute chest pain due to coronary artery disease. PAPP-A is a metalloproteinase widely used for the screening of fetal trisomy during the first trimester of pregnancy. Unusually low levels at 8 to 14 weeks of gestation indicate an increased risk of intrauterine growth restriction, trisomy 21, premature delivery, preeclampsia, and stillbirth. PAPP-A is also abundantly expressed by unstable atherosclerotic plaques and as a marker of plaque stability; its level is a strong independent predictor of cardiovascular events in patients with acute coronary syndromes.

PROGESTERONE


Progesterone is an important female sex hormone. Progesterone levels are normally elevated during the reproductive period of a woman’s life and become lower during menopause. Progesterone is produced by the corpus luteum and is necessary for proper uterine and breast development and function. Its levels are low during the follicular phase of the menstrual cycle and high during the luteal phase; they continue to rise during early pregnancy. High progesterone levels suggest pregnancy, ovarian cancer, or adrenal cancer, while low levels may occur in amenorrhea, fetal death, and toxemia of pregnancy. Synthetic progestins have been linked to the risk of heart disease, but more research is needed to confirm this relationship.

PROLACTIN


Prolactin is a hormone that is made in the pituitary gland and helps to initiate and maintain milk production in women. Its levels are naturally high while breast-feeding, but high levels at other times may indicate disease. Physiologically, it initiates and maintains lactation; its release is primarily stimulated by suckling. Causes of hyperprolactinemia include pituitary tumors, hypothalamic disease or injury, chronic renal failure, multiple sclerosis, hypothyroidism, ectopic tumors, syringomyelia, tabes dorsalis, breast trauma, polycystic ovarian syndrome, and hepatic cirrhosis. Prolactin levels are useful in the evaluation of pituitary tumors and their treatment, as well as the assessment of hypothalamic abnormalities, infertility, amenorrhea, and galactorrhea.

PROLIFERATING CELL NUCLEAR ANTIGEN ANTIBODY(PCNA Ab)


Proliferating cell nuclear antigen (PCNA) is an important enzyme in the synthesis and repair of DNA. In patients with systemic lupus erythematosus, antibodies to PCNA are associated with kidney damage, nervous system damage, and low platelet counts. PCNA antibodies have also been found in patients with chronic hepatitis. The presence of PCNA autoantibodies is associated with renal and CNS involvement and thrombocytopenia in patients with systemic lupus erythematosus (SLE). PCNA autoantibodies have been detected in up to 31% of SLE patients; autoantibody titers are elevated prior to the development of proteinuria and decrease following corticosteroid treatment. Antibodies to PCNA have also been observed in patients with chronic hepatitis B or C infection. PCNA is also known as DNA polymerase-d auxiliary protein.

PROSTATE-SPECIFIC ANTIGEN, FREE(PSA, FREE)


Prostate-specific antigen (PSA) is highly specific for prostate tissue, and its levels may be increased in prostate cancer, benign prostatic hyperplasia (BPH), and prostatitis. Most of the measurable PSA in serum is complexed with alpha-1-antichymotrypsin, but PSA also occurs in a free form. A total PSA of 3.0 to 4.0 ng/ml with a free PSA less than 19% suggests prostate cancer, as does a total PSA above 4.0 ng/ml with a free PSA less than 24%. In about 70% of cases, a significant increase in PSA levels indicates prostate cancer, but because many prostate cancer patients have normal PSA levels, diagnosis also involves digital rectal examination and transrectal ultrasonography.

PROSTATE-SPECIFIC ANTIGEN, TOTAL(PSA, TOTAL)


Prostate-specific antigen (PSA) is highly specific for prostate tissue and its levels may be increased in prostate cancer, benign prostatic hyperplasia (BPH), and prostatitis. Most of the measurable PSA in serum is complexed with alpha-1-antichymotrypsin, but PSA also occurs in a free form. A total PSA of 3.0 to 4.0 ng/ml with a free PSA less than 19% suggests prostate cancer, as does a total PSA above 4.0 ng/ml with a free PSA less than 24%. In about 70% of cases, a significant increase in PSA levels indicates prostate cancer, but because many prostate cancer patients have normal PSA levels, diagnosis also involves digital rectal examination and transrectal ultrasonography.

PROSTATIC ACID PHOSPHATASE(PAP)


Prostatic acid phosphatase (PAP) is found primarily (but not solely) in the prostate gland and the semen. PAP levels may be abnormal in a number of conditions, including prostate cancer, Paget’s disease, anemia, infection, thrombophlebitis, Gaucher’s disease, hyperparathyroidism, myocardial infarction, and multiple myeloma. They may also be transiently elevated after prostatic massage, needle biopsy, or cystoscopy. PAP levels may be used in the staging of prostate carcinoma, the diagnosis of metastatic adenocarcinoma of the prostate, and the monitoring of prostate cancer therapy.

PROTEINASE 3 ANTIBODY(PR3 Ab)


The presence of antibodies against the proteinase 3 enzyme (which is produced by white blood cells in patients with certain autoimmune diseases) appears to be associated with autoimmune conditions such as Wegener’s granulomatosis. Levels of these antibodies can be used to monitor the activity of these diseases. Proteinase 3 (PR3), found in the granules of neutrophils and monocytes in patients with Wegener’s granulomatosis, is the major target antigen for anti-neutrophil cytoplasmic autoantibodies (ANCAs). PR3 autoantibodies are sensitive and specific markers for Wegener’s granulomatosis and can be used to monitor disease activity.

RED BLOOD CELL COUNT(RBC COUNT)


The red blood cell count (RBC count) indicates the absolute number of red blood cells in the blood. An abnormally high erythrocyte count may be associated with cardiovascular disease, polycythemia vera, tobacco abuse, renal cell carcinoma, stress, high altitude, or dehydration. An abnormally low count may indicate anemia, acute hemorrhage, marrow failure, or chronic renal failure.

RED CELL DISTRIBUTION WIDTH(RDW)


This test measures the variability in size of the red blood cell population. When used in conjunction with mean corpuscular volume (MCV), this test is useful in diagnosing a variety of conditions.

REGULATED UPON ACTIVATION, NORMAL T-CELL EXPRESSED AND SECRETED(RANTES)


Regulated upon activation, normal T-cell expressed and secreted (RANTES) is a protein that attracts various types of white blood cells and brings them to sites of inflammation. Levels of RANTES may be elevated in inflammatory and allergic conditions. RANTES (also called CCL5) is produced by T-cells and is chemotactic for T-cells, eosinophils, and basophils. It plays an active role in recruiting leukocytes to inflammatory sites and also activates eosinophils and basophils and stimulates IgE production.

RESPIRATORY SYNCYTIAL VIRUS ANTIBODY(RSV Ab)


Respiratory syncytial viruses (RSV) may cause serious respiratory tract infections in infants and young children. The presence of the antibody against RSV indicates exposure to or infection with this virus but does not protect against being infected with it again. RSV can be fatal, and sudden deaths occurring in infants with respiratory disease are often believed to be due to this virus. In older children and adults, RSV may cause an influenza-like syndrome, bronchopneumonia, or exacerbations of chronic bronchitis. Although about 70% of the population have serum antibodies to RSV by the age of 5, these antibodies are not considered protective, since reinfection can occur.

RHEUMATOID FACTOR(RF)


Rheumatoid factor (RF) is an immune system protein whose presence generally indicates one of a variety of autoimmune diseases. RF levels are particularly high in rheumatoid arthritis and Sjögren’s syndrome. Serum rheumatoid factor represents the immune system response to the presence of a “non-self” immunoglobulin molecule, which results in the formation of immune complexes. These bind complement and may eventually lead to synovium, cartilage, and bone destruction. RF may be found in a variety of autoimmune diseases, including rheumatoid arthritis (80% to 90%), Sjögren’s syndrome (75% to 95%), systemic lupus erythematosus (15% to 35%), scleroderma (20% to 30%), polymyositis or dermatomyositis (10%), and mixed connective tissue disease (50% to 60%). It also occurs in up to 10% of apparently healthy individuals, with an incidence that increases with age. In addition, RF assays may be positive in some patients with syphilis, osteomyelitis, tuberculosis, bacterial endocarditis, hepatitis, mononucleosis, cirrhosis, sarcoidosis, or diffuse interstitial pulmonary fibrosis.

RIBOSOMAL NUCLEAR PROTEIN ANTIBODY


Ribosomal nuclear protein (RNP) antibodies are antibodies against molecules in the nuclei of our cells. Antibodies to nuclear antigens are strongly associated with collagen vascular diseases including systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), progressive systemic sclerosis (PSS), and Sjögren’s syndrome (SS). RNP antibodies are found in 95% to 100% of patients with MCTD and are considered specific for this syndrome if other antibodies are negative. They also occur in 20% to 30% of patients with SLE and 15% to 25% of patients with progressive systemic sclerosis (PSS).

RIBOSOMAL NUCLEAR PROTEIN A ANTIBODY(RNP A Ab)


Ribosomal nuclear protein A (RNP A) antibodies are antibodies against molecules in the nuclei of our cells. Antibodies to nuclear antigens are strongly associated with collagen vascular diseases, including systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), progressive systemic sclerosis (PSS), and Sjögren’s syndrome. RNP antibodies are found in 95% to 100% of patients with MCTD and are considered specific for this syndrome if other antibodies are negative. They also occur in 20% to 30% of patients with SLE and 15% to 25% of patients with progressive systemic sclerosis (PSS).

RIBOSOMAL NUCLEAR PROTEIN C ANTIBODY(RNP C Ab)


Ribosomal nuclear protein C (RNP C) antibodies are antibodies against molecules in the nuclei of our cells. Antibodies to nuclear antigens are strongly associated with vascular diseases, including systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), progressive systemic sclerosis (PSS), and Sjögren’s syndrome. RNP antibodies are found in 95% to 100% of patients with MCTD and are considered specific for this syndrome if other antibodies are negative. They also occur in 20% to 30% of patients with SLE and 15% to 25% of patients with progressive systemic sclerosis (PSS).

RIBOSOMAL P ANTIBODY


Ribosomal P antibodies are antibodies against one of the parts of our cells. Autoantibodies against cytoplasmic ribosomes are highly specific for systemic lupus erythematosus (SLE) and are considered markers. Ribosomal P antibodies are found in about 12% of patients with SLE and in 90% of those with lupus psychosis.

RUBELLA ANTIBODY


Rubella (also called “German measles”) is a contagious but mild disease that causes a rash, a fever, and swollen lymph glands. Rubella syndrome refers to the devastating birth defects that affect about a quarter of the fetuses exposed to rubella during pregnancy. Rubella syndrome is a spectrum of congenital defects that can include cataracts, deafness, glaucoma, congenital heart disease, microcephaly, growth retardation, and mental retardation. Between 10% and 20% of newborns infected in utero fail to survive for 12 months. Since these complications are so severe, diagnosis of infection during the first trimester may affect the decision to terminate or continue the pregnancy. It is important, therefore, to determine the rubella immune status in women of child-bearing age, pregnant women, and individuals who may have close contact with them. In a primary rubella infection, the appearance of both IgG and IgM antibodies is associated with the appearance of clinical signs and symptoms when present. IgM antibodies become detectable a few days after the onset of signs and symptoms and reach peak levels in 7 to 10 days. Their level then diminishes over the next 4 to 5 weeks until they are no longer clinically detectable. Rubella IgM antibodies in a newborn’s serum suggest congenital infection, since IgM from the mother is not transferred across the placenta, and may persist for several months.

RUBEOLA ANTIBODY


The presence of antibodies against rubeola (the measles virus) indicates recent vaccination against this virus, exposure to it, or infection with it. Since mass immunization began in the United States over two decades ago, the number of measles infections has been greatly reduced, although many individuals remain susceptible due to vaccine failure or non-immunization. The presence of measles antibodies confirms seroconversion after vaccination and is useful in the evaluation of the rare but fatal subacute sclerosing panencephalitis (SSPE), which may occur years after the original measles infection.

SCLERODERMA 70 ANTIBODY(Scl-70 Ab)


The presence of the scleroderma 70 (Scl-70) antibody indicates an autoimmune condition called scleroderma. However, it may also occur in other connective tissue and rheumatic diseases such as systemic lupus erythematosus. When Scl-70 antibody is the only autoantibody present, it is a specific marker for scleroderma, although Scl-70 antibodies are also seen in 25% of progressive systemic sclerosis patients. These antibodies are more prevalent in patients with diffuse scleroderma (>70%) compared with those with milder disease.

SERUM AMYLOID P(SAP)


Serum amyloid P (SAP) is a protein that is found in normal serum and in amyloid plaques (protein deposits in the tissues) and involved in immune system responses. Elevation of amyloid P levels may be an indicator of liver disease or neurological disorders such as Alzheimer’s disease. Amyloid P prevents fibrillar breakdown by enzymes, interacts with inflammatory and complement factors, modulates immunologic responses, and inhibits elastase.

SEX HORMONE-BINDING GLOBULIN(SHBG)


Abnormal levels of sex hormone-binding globulin (SHBG) may occur in a variety of diseases or in pregnancy. SHBG is a beta-globulin that binds sex hormones with a high affinity for dihydrotestosterone and a low affinity for estradiol. Levels of SHBG are under the positive control of estrogens and thyroid hormones and are suppressed by androgens. Decreased SHBG levels may occur in hirsutism, virilization, obese postmenopausal women, and women with diffuse hair loss. Increased levels may occur in hyperthyroidism, testicular feminization, cirrhosis, male hypogonadism, pregnancy, and during oral contraceptive use.

SMITH ANTIBODY(SM Ab)


The presence of the Smith (Sm) antibody suggests the presence of an autoimmune disease such as systemic lupus erythematosus, mixed connective tissue disease, progressive systemic sclerosis, or Sjögren’s syndrome. Sm antibodies (also called anti-Smith antibodies) are highly specific for SLE but occur in only 30% to 35% of cases; they are often associated with lupus nephritis. In SLE patients, the presence of RNP antibodies is associated with a relatively benign course, while the presence of Sm antibodies without RNP antibodies indicates a high risk of renal and central nervous system involvement. Increased titers of Sm antibody predict disease relapse in 50% of patients.

SODIUM(Na)


Sodium (Na) is an important positively charged electrolyte that is vital to cell functions. Its levels in the body are tightly controlled by many hormonal and metabolic mechanisms. Sodium levels may be abnormal in a variety of diseases. Sodium is the major positive ion in extracellular fluid. Many factors affect sodium levels, including aldosterone, which reduces sodium loss in the urine. Hypernatremia may occur in burns, excessive sweating, diarrhea, diabetes insipidus, hyperaldosteronism, Cushing’s syndrome, acute tubular necrosis, or after ingesting salt or sodium bicarbonate or using osmotic or loop diuretics. Hyponatremia may be due to dehydration, overdiuresis, ketonuria, vomiting, diarrhea, syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypothyroidism, Addison’s disease, kidney failure, congestive heart failure, nephrotic syndrome, or cirrhosis.

SSA ANTIBODY


SSA antibodies react to molecules in the nuclei of our cells. Antibodies to nuclear antigens are hallmarks of collagen vascular diseases including systemic lupus erythematosus (SLE), mixed connective tissue disease, progressive systemic sclerosis (PSS), and Sjögren’s syndrome. SSA (Ro) antibodies are found in 70% to 75% of patients with Sjögren’s syndrome, 30% to 40% of patients with SLE, and 5% to 10% of patients with PSS. SSB (La) antibodies are found in about 50% to 60% of patients with Sjögren’s syndrome but are only specific markers when they are the sole antibodies to extractable nuclear antigen present. Some 15% to 25% of SLE patients and 5% to 10% of PSS patients also carry this antibody. SSA antibodies appear to be strongly associated with neonatal SLE and congenital heart block.

SSB ANTIBODY


SSB antibodies react to molecules in the nuclei of our cells. Antibodies to nuclear antigens are hallmarks of collagen vascular diseases, including systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), progressive systemic sclerosis (PSS), and Sjögren’s syndrome (SS). SSA and SSB antibodies have been found in some patients who have clinical features of SLE, including prominent cutaneous features, but who frequently fail to demonstrate a positive anti-nuclear antibody. Several studies point to the use of SSB antibodies as a serological marker for Sjögren’s syndrome-sicca complex, since they are detected in about 60% of these patients.

STEM CELL FACTOR(SCF)


Stem cell factor (SCF) is a cytokine (cell signaling protein) synthesized by various connective tissues. It stimulates the production of stem cells, which mature into all the different types of blood cells. SCF may be useful in the treatment of a variety of bone marrow and blood disorders. SCF is a stromal cell-derived cytokine. Its ability to induce differentiation in lymphoid and erythroid progenitor cells and mast cells gives it potential relevance in the treatment of myelodysplastic syndromes and post-bone marrow transplant patients. SCF has been shown to improve in vitro erythropoiesis in several types of inherited marrow failure syndromes, including Diamond-Blackfan anemia, Fanconi’s anemia, dyskeratosis congenita, amegakaryocytic thrombocytopenia, and transient erythroblastopenia of childhood.

STREPTOLYSIN O ANTIBODY


Antibodies against streptolysin O indicate previous infection with a bacterium of the Streptococcus type. Group A streptococcal infection may cause acute rheumatic fever, acute kidney conditions, and skin infections. The streptolysin O antibody (ASO) test provides serologic evidence of previous group A streptococcal infection in patients suspected of having a non- suppurative complication, such as acute glomerulonephritis or acute rheumatic fever. Elevated serum ASO titers are found in 80% to 85% of individuals with rheumatic fever, but skin infections with group A streptococci are often associated with a poor ASO response.

TESTOSTERONE


Testosterone is the major male sex hormone and is produced in the testes. It controls male sexual development and reproduction. Testosterone levels increase during puberty to an adult peak but may decrease in the elderly male. Abnormal testosterone levels may also occur in several glandular conditions. Testosterone is produced by the Leydig cells of the testes. In adult males, testosterone levels show a diurnal variation, with the highest levels detected in the early morning. Levels also increase after exercise and gradually decrease with age. In women, testosterone levels are 5% to 10% of those in males. Only 2% to 3% of testosterone circulate in the free, biologically active form; the remainder is bound to sex hormone-binding globulin or albumin. Serum concentrations of free testosterone are less than 1.5 pg/ml in prepubertal children and increase during puberty to adult values at a rate determined by pubertal stage. Clinical syndromes, in which serum testosterone is increased, include gonadal and adrenal tumors, adrenal hyperplasia, and polycystic ovarian syndrome. Decreased testosterone levels occur in hypogonadism, hypopituitarism, orchiectomy, estrogen therapy, and some cases of Klinefelter’s syndrome.

TETANUS ANTIBODY


Tetanus is a serious infectious disease caused by bacteria. The presence of antibodies against tetanus indicates recent vaccination against, exposure to, or infection with tetanus. Immunization against the tetanus toxin is a very effective preventative measure.

THROMBOPOIETIN(TPO)


Thrombopoietin (TPO) is a protein that stimulates the increase in the size and number of the cells (called megakaryocytes) that are broken down to create platelets. TPO stimulates an increase in megakaryocyte size and number, DNA content, endomitosis, and maturation. It also increases the number of small acetylcholinesterase-positive cells that are early precursor cells of the megakaryocytic lineage. Although interleukin-6 stimulates megakaryocyte production in vitro and increases platelet counts in vivo, it does not appear to be the only factor with TPO activity. TPO is also referred to as c-Mp1 ligand, Mpl ligand, megapoietin, and magakaryocyte growth and development factor.

THYROGLOBULIN ANTIBODY


Antibodies against thyroglobulin may be present in patients with autoimmune thyroiditis (Hashimoto’s thyroiditis) and may confuse the results of thyroglobulin tests. However, detection of these antibodies can help to predict the progression of clinical thyroiditis, to substantiate thyroid disease in patients with non-thyroidal illnesses, and to predict postpartum thyroiditis. In addition, more than 90% of patients with autoimmune thyroiditis (Hashimoto’s thyroiditis) have thyroglobulin or thyroid microsomal antibodies.

THYROGLOBULIN ANTIGEN


Thyroglobulin is a protein that binds to thyroxine (T4). Its levels may be elevated in inflammatory conditions of the thyroid as well as in thyroid cancer. Serum thyroglobulin levels are particularly useful in thyroid cancer monitoring, since localized or metastatic thyroid carcinomas increase these levels, but they fall again after complete thyroidectomy and 131I ablation therapy. Thyroglobulin levels are also elevated in Graves’ disease, endemic goiter, and silent (painless) thyroiditis but are low or normal in patients with thyrotoxicosis factitia resulting from the surreptitious intake of thyroid hormone.

THYROID MICROSOMAL ANTIBODY


Combined with the test for thyroglobulin antibodies, the presence of antibodies against thyroid microsomal antigens (molecules in thyroid cells) can detect most autoimmune thyroid conditions. This combined testing for autoantibodies can detect almost all goitrous thyroiditis (Hashimoto’s disease), almost all atrophic thyroiditis (myxedema), and about 70% to 90% of cases of Graves’ disease. However, thyroid microsomal autoantibodies (TMAs) are found in about 6% to 7% of adult Caucasians, and their prevalence increases with age. Even in asymptomatic individuals, the presence of TMAs can be predictive of hypothyroidism and does not exclude thyroid cancer. When total and free thyroid hormone levels do not match clinical findings, the presence of autoantibodies should be determined. In addition, TMA testing is thought to be a cost-effective screening method for postpartum thyroid dysfunction.

THYROID STIMULATING HORMONE(TSH)


Thyroid stimulating hormone (TSH) is produced in the pituitary gland and stimulates the thyroid to secrete T4 and T3 thyroid hormones. Abnormal levels of TSH may indicate various thyroid and pituitary gland conditions. Thyroid stimulating hormone, or thyrotropin, is a glycoprotein synthesized and secreted by the pituitary gland. It stimulates synthesis and secretion of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Secretion of TSH is stimulated by thyrotropin-releasing hormone, a hypothalamic tripeptide, and regulated via negative feedback through thyroid hormone levels. Increased serum levels of free T4 and T3 depress TSH secretion (hyperthyroidism), while decreased serum levels of free T4 and T3 result in excess TSH secretion (primary hypothyroidism). Serum TSH concentration is inversely proportional to the free T4 concentration in a log/linear relationship, making TSH a sensitive marker for monitoring the effects of thyroid hormone replacement therapy.(TSH)

THYROXINE(T4)


Thyroxine (T4) is the most abundant thyroid hormone and plays an important role in the control of metabolism. The majority of circulating triiodothyronine (T3) results from the conversion of T4 in the peripheral tissues. In serum, T4 is bound to thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin. The serum-free T4 concentration is about 0.03% of the total T4 concentration. Increased free T4 levels may result from Graves’ disease, toxic adenoma, toxic multinodular goiter, thyroiditis, and (rarely) thyroid cancer. Decreased levels may result from thyroiditis, idiopathic myxedema, pituitary dysfunction, hypothalamic disease, or the use of certain medications.

THYROXINE ANTIBODY(T4 Ab)


The thyroxine antibody test measures antibodies to T4 thyroid hormone. Autoantibodies to T4 can alter the results of the T4 test and may indicate an underlying autoimmune condition.4

THYROXINE BINDING GLOBULIN(TBG)


Thyroxine binding globulin (TBG) binds to T4 thyroid hormone in the bloodstream. Determination of thyroxine binding globulin levels is particularly useful when total thyroid hormone levels do not correlate with the thyro- metabolic status, as in pregnancy, contraceptive steroid use, or hereditary excesses or deficiencies of TBG.

TISSUE FACTOR(TF)


Tissue factor (TF) is a membrane receptor protein that behaves like a cytokine (a cell signaling molecule). It is involved in blood coagulation and helps to signal other cells involved in inflammatory reactions. Levels of tissue factor may be elevated in cancer and certain inflammatory conditions. Tissue factor is an integral membrane receptor glycoprotein and a type-2 cytokine receptor. It initiates both extrinsic and intrinsic cascades by forming high- affinity complexes between its extracellular domain and circulating blood coagulation Factors VII and VIIa. These enzymatically active complexes then activate Factors IX and X, leading to thrombin generation and clot formation. TF is expressed on extravascular and perivascular cells but not vascular endothelial cells or monocytes. Up-regulation of tumor TF correlates with enhanced metastatic potential.

TISSUE INHIBITOR OF METALLOPROTEINASE 1(TIMP-1)


Tissue inhibitors of metalloproteinases (TIMPs) block the activity of matrix metalloproteinases (MMPs), enzymes that break down structural proteins and connective tissue. It is believed that levels of TIMPs and MMPs should be balanced for good health. Metalloproteinases of the extracellular matrix are proteolytic enzymes involved in the biosynthesis of connective tissue. The synthesis and secretion of matrix metalloproteinases (MMPs) are induced in various cell types by cytokines. MMPs degrade constituents of the basal membrane and the extracellular matrix (including collagens, proteoglycans, gelatin, fibronectin, laminin, and elastin) under physiological and pathological conditions. Their activities also facilitate the invasive migration of cells. These biological activities are subject to a complex regulation involving TIMPs (tissue inhibitors of metalloproteinases) and many MMP proforms form complexes with these inhibitors. TIMP-1 is a major regulator of extracellular matrix synthesis and degradation.

TISSUE TRANSGLUTAMINASE ANTIBODY(tTG Ab)


The presence of antibodies against tissue transglutaminase is associated with celiac disease, a digestive condition associated with poor absorption of nutrients. Symptoms include abdominal pain, constipation, diarrhea, and bloating. Celiac disease occurs most often in childhood and in the third to fifth decades of life but can develop at any age. The typical presentation is malabsorption, but subclinical disease, particularly in adults, can be intestinal or extraintestinal and can include symptoms similar to irritable bowel syndrome, including bloating, abdominal pain, constipation, or diarrhea. Other symptoms can include anemia, fatigue, dyspepsia, infertility, miscarriages, bone pain, tooth enamel defects, oral ulcers, elevated aminotransferases, and neurologic or neuropsychiatric manifestations. In children, initial manifestations include diarrhea, vomiting, failure to thrive, short stature, irritability, delayed puberty, and recurrent abdominal pain with bloating. Although many patients present with multiple symptoms, it is not uncommon for a patient to have a single sign or symptom.

TOTAL PROTEIN


Total protein is a measure of the total protein content in the blood. Total protein levels are used in the evaluation of nutritional status, nephrotic syndromes, malabsorption, neoplasia including myeloma, and Waldenstrom’s macroglobulinemia. Protein levels may be elevated due to dehydration, vomiting, diarrhea, Addison’s disease, diabetic acidosis, or multiple myeloma. They are decreased in nephrotic syndrome, salt retention syndromes, severe burns, extensive bleeding, open wounds, sprue, intestinal malabsorption, and severe protein starvation (kwashiorkor).

TOXOPLASMA GONDI ANTIBODY


Toxoplasmosis is a common infectious disease, caused by the Toxoplasma gondi parasite, that may be fatal to a fetus or immunocompromised patients. In healthy individuals, it causes only mild symptoms. Antibodies against the parasite that causes toxoplasmosis indicate recent infection with this parasite. Acute toxoplasmosis in pregnant women can result in severe damage to or the death of the fetus.

TRIGLYCERIDES


Triglycerides are common fats found in the food we eat and in our bodies. High blood levels of triglycerides are related to dietary intake as well as metabolic factors. Triglycerides are often measured as a reflection of fat ingestion and metabolism or as part of an evaluation of coronary risk factors. High triglyceride levels appear to be associated with an increased risk of cardiovascular events, particularly in conjunction with other risk factors. High triglyceride levels may occur in cirrhosis, chronic renal insufficiency, familial hyperlipoproteinemia (rare), acute myocardial infarction, hypothyroidism, diabetes mellitus, Cushing’s syndrome, nephrotic syndrome, glycogen storage disease, and pancreatitis. Low levels may indicate malabsorption syndrome, malnutrition, or abetalipoproteinemia.

TRIIODOTHYRONINE(T3)


Triiodothyronine (T3) is a thyroid hormone that is important in body metabolism. About 80% of triiodothyronine result from conversion of thyroxine (T4) to T3 in peripheral tissues, while the remaining 20% are synthesized by the follicular cells of the thyroid gland. Free T3 levels generally correlate closely with total T3 levels; however, total T3 is affected by levels of thyroid hormone- binding proteins, while free T3 is not. Thus, TBG elevations due to pregnancy, oral contraceptive use, or estrogen therapy will increase total T3 without affecting the free T3 concentration. Measurement of total T3 by immunoassay can be used to evaluate hyperthyroidism when an elevated free or total thyroxine (T4) level has been encountered.

TRIIODOTHYRONINE ANTIBODY(T3 Ab)


The triiodothyronine antibody test measures antibodies to T3 thyroid hormone. Autoantibodies to T3 can alter the results of the T3 test and may indicate an underlying autoimmune condition.

TRYPANOSOMA CRUZI ANTIBODY(T. CRUZI Ab)


Trypanosoma cruzi is an infectious parasite that can cause Chagas’ disease or American trypanosomiasis. This is relatively common in South America and other developing regions, but rare in the United States. The presence of antibodies against Trypanosoma cruzi indicates prior exposure to or infection with Trypanosoma cruzi.

TUMOR NECROSIS FACTOR ALPHA(TNF-ALPHA)


Tumor necrosis factor alpha (TNF-alpha) is produced by various white blood cells, including macrophages, monocytes, neutrophils, and some lymphocytes. It attacks cancer cells. Levels of TNF-alpha may be elevated in cancers (especially lung cancer and certain leukemias) and some inflammatory conditions. TNF-alpha is secreted after stimulation with interferon, interleukin-2, granulocyte/macrophage colony-stimulating factor, bradykinin, immune complexes, cyclooxygenase inhibitors, or platelet activating factor. Unlike chemotherapeutic drugs, TNF-alpha attacks only malignant cells; preclinical studies have documented a direct cytostatic and cytotoxic effect against cancer cells, as well as a variety of immunomodulatory effects on immune effector cells, including neutrophils, macrophages, and T-cells. Unfortunately, while clinical trials have confirmed the safety of TNF-alpha, they have so far failed to demonstrate significant efficacy. TNF-alpha is also found in the synovial fluid of arthritis patients, and it has been suggested that inhibitors would be therapeutically beneficial. Other disorders in which TNF- alpha may play a role include systemic inflammatory response syndrome, hairy cell leukemia, and fibrosarcoma.

TUMOR NECROSIS FACTOR BETA(TNF-BETA)


Tumor necrosis factor beta (TNF-beta) is produced by white blood cells and promotes the generation of cells involved in wound healing. TNF-beta may also inhibit the growth of some cancers by decreasing their production of new blood vessels. Levels of TNF-beta may be elevated in certain infections, especially meningococcal septicemia, and some tumors. TNF-beta is produced predominantly by mitogen-stimulated T-lymphocytes and secreted by fibroblasts, astrocytes, myeloma cells, endothelial cells, epithelial cells, and a number of transformed cell lines. Its synthesis is stimulated by interferons and interleukin-2. TNF-beta promotes the proliferation of fibroblasts and appears to be involved in wound healing processes and possibly anti-tumor activities. However, clinical applications are only in initial stages. In addition, TNF-beta levels in the sera of patients with meningococcal septicemia have been shown to correlate with morbidity and mortality.

TUMOR NECROSIS FACTOR RECEPTOR 2(TNF R2)


The tumor necrosis factor receptor 2 (TNF R2) molecule is involved in the destruction of various types of normal and abnormal proteins. Low levels of TNF R2 are associated with cancer of the kidney. This protein binds to the intracellular domain of the type 1 TNF receptor. It has been shown to be identical with subunit 2 of the 26S proteasome complex, which mediates the degradation of constitutively short-lived proteins, regulatory proteins, and abnormal and malfolded proteins. Its expression is down-regulated in renal carcinoma cells.

URIC ACID


Uric acid elevations may occur in gout, renal disease with renal failure, dehydration, diuretic use, alcoholism, lead poisoning, lymphoma, leukemia, infectious mononucleosis, acute inflammatory state, acidosis, hyperparathyroidism, hypothyroidism, sarcoidosis, toxemia of pregnancy, chemotherapy, and radiation therapy. Uric acid levels may also be useful as an indicator of renovascular involvement in essential hypertension. Causes of low uric acid levels include Wilson’s disease, Fanconi syndrome, hemochromatosis, xanthine-oxidase deficiency, syndrome of inappropriate secretion of antidiuretic hormone (SIADH), and the use of certain drugs.

VARICELLA ZOSTER IgG ANTIBODY(V. ZOSTER IgG Ab)


Varicella zoster virus is the infectious agent that causes chickenpox and shingles. The presence of IgG antibodies against Varicella zoster virus indicates prior exposure to this virus.

VARICELLA ZOSTER IgM ANTIBODY(V. ZOSTER IgM Ab)


Varicella zoster virus is the infectious agent that causes chickenpox and shingles. The presence of IgM antibodies against Varicella zoster virus indicates infection with this virus.

VASCULAR CELL ADHESION MOLECULE 1(VCAM-1)


Vascular cell adhesion molecule 1 (VCAM-1) is a molecule that helps in the adhesion of various white blood cells, including lymphocytes, monocytes, natural killer cells, eosinophils, and basophils. Levels of VCAM-1 may be elevated in certain inflammatory conditions. VCAM-1 interacts with leukocyte very late antigen-4 (VLA-4). This interaction mediates the firm adherence of circulating non-neutrophilic leukocytes to endothelium. VCAM-1 also participates in leukocyte adhesion outside the vasculature, mediating precursor lymphocyte adhesion to bone marrow stromal cells, and B-cell binding to lymph node follicular dendritic cells. VCAM-1 is not constitutively expressed on endothelium but is present on tissue macrophages, dendritic cells, bone marrow fibroblasts, myoblasts, and myotubes. A soluble form of VCAM-1 (sVCAM-1) has been described; sVCAM-1 has been found in the serum of healthy individuals, and increased levels have been detected in several diseases.

VASCULAR ENDOTHELIAL GROWTH FACTOR(VEGF)


Vascular endothelial growth factor (VEGF) promotes the development of new blood vessels. Its levels may be elevated in neuronal and other tumors. VEGF is important in the pathophysiology of neuronal and other tumors, probably as a potent promoter of angiogenesis. Its synthesis is also induced by hypoxia. Due to its effects on vascular permeability, VEGF may be involved in altering blood-brain-barrier functions under normal and pathological conditions. Its release by glioma cells may account for clinical features of glioblastoma multiforme tumors, including striking tumor angiogenesis, increased cerebral edema and hypercoagulability manifesting as focal tumor necrosis, deep vein thrombosis, and pulmonary embolism. VEGF secreted by stromal cells may be responsible for endothelial cell proliferation in capillary hemangioblastomas, and the production and secretion of VEGF by human retinal pigment epithelial cells may play a role in the pathogenesis of ocular neovascularization.

VITAMIN B12(ALSO CALLED COBALAMIN)


Vitamin B12 is important in normal cell growth and multiplication. Vitamin B12 deficiency may result in neurologic conditions or anemia. Vitamin B12 (cobalamin) is critical to normal DNA synthesis. The body excretes very little B12, instead reabsorbing it from the ileum and returning it to the liver. Clinical and laboratory findings in B12 deficiency include neurological abnormalities, decreased serum B12 levels, increased excretion of methylmalonic acid, and a macrocytic anemia characterized by the abnormal megaloblastic maturation of erythrocyte precursors. The neurologic abnormalities probably result from defective myelin synthesis and the accumulation of abnormal lipids. Causes of low vitamin B12 levels include low intake, pernicious anemia, gastrectomy, diseases of the small intestine, malabsorption, and transcobalamin deficiency.

von WILLEBRAND FACTOR(vWF)


The von Willebrand factor (vWF) is a protein made in the cells lining blood vessels and the large cells that eventually become platelets (megakaryocytes). It plays an important role in the clumping of platelets and resulting clot formation. Abnormal levels of von Willebrand factor may result in bleeding disorders. The von Willebrand factor antigen (vWF:Ag) is synthesized in endothelial cells and megakaryocytes as a number of subunits that polymerize and combine with Factor VIII to form a large complex. In the plasma, von Willebrand factor (also known as ristocetin cofactor or RCF) exists as a heterogenous population of large polymers to which Factor VIII is complexed by non-covalent bonds. The vWF:Ag level is an immunologic measure of vWF levels and one component of a “von Willebrand’s panel.” Patients with a chronic bleeding disorder and a family history of bleeding should be evaluated for von Willebrand’s disease; vWF:Ag levels are decreased in von Willebrand’s disease (vWD) patients and normal in hemophilia A patients and carriers. Since many variants of vWD exist, identification is more likely if Factor VIII activity, vWF:Ag, and vWF-RCF activity are all assayed. Because many vWD patients have mild disease, repeated testing may be necessary in order to make the diagnosis. Female patients with vWD who are pregnant or taking oral contraceptives may have normal vWF:Ag values.

WHITE BLOOD CELL COUNT(WBC COUNT)


This test measures the total number of white blood cells present in the blood. White blood cells are the major infection-fighting cells but are also involved in immune system responses to allergens, tumors, and cell stress. Leukopenia may indicate bone marrow failure, the presence of a cytotoxic substance, collagen vascular disease (such as systemic lupus erythematosus), liver disease, spleen disease, or radiation. Leukocytosis may indicate infectious disease, inflammatory disease (such as rheumatoid arthritis or allergy), leukemia, severe emotional or physical stress, or tissue damage.

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