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| Clinical
Chemistry Screen and Marker Descriptions
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ANEMIA SCREEN |
Iron: Iron is a necessary building block for hemoglobin, a major component of red blood cells. The hemoglobin molecule binds oxygen and delivers it to the tissues throughout the body. Iron is also used in other cells in the body, particularly muscle where it is part of myoglobin.
Total Iron Binding Capacity: A test that shows if there is too much or too little iron in the blood. This test helps measure the ability of a protein called transferrin to carry iron in the blood.
Percent Iron Saturation: (Iron divided by Iron Binding Capacity) – Represents the percentage of available transferrin sites occupied by iron.
Ferritin: About 30% of the iron in the body is stored as ferritin in the liver, bone marrow and spleen. Ferritin is composed of 24 identical protein subunits that store iron ions for future use. The amount of ferritin in the body reflects the amount of iron stored in the body.
Transferrin: Transferrin is the protein that transports iron in the blood. Most transferrin is produced in the liver. Transferrin regulates the release of iron from storage into the general circulation.
HGB: This test measures the amount of hemoglobin, a protein that is found in red blood cells, and is a good indication of your blood’s ability to carry oxygen throughout your body.
Vitamin B-12 and Folate: B-12 and folate are B complex vitamins that are necessary for normal red blood cell formation, tissue and cellular repair, and DNA synthesis. A B-12 and/or folate deficiency reflects a chronic shortage of one or both of these vitamins.
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AUTO-IMMUNE SCREEN |
RA Factor (Latex Fixation): This test detects and measures rheumatoid factor (RF) in the blood. RF is an autoantibody that is produced by the body’s immune system. Autoantibodies usually attack the patient’s own tissues, mistakenly identifying them as “foreign.” While the role of RF is not well understood, it is not thought to directly cause joint damage but to promote the body's inflammation reaction, which in turn contributes to autoimmune tissue destruction. The RF test is sensitive but nonspecific. It is most closely associated with rheumatoid arthritis (RA) but may also be present in a variety of other autoimmune disorders.
ANA Screen: Identifies the presence of antinuclear antibodies (ANA) in blood. Sometimes the immune system malfunctions and produces substances that attack the body's own cells and tissues instead of foreign substances. These substances, called autoantibodies, are produced by the immune system. The presence of ANA is a marker of an autoimmune process and is associated with several autoimmune diseases but is most commonly seen in systemic lupus erythematosus (SLE).
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BASIC LIPID PANEL |
Cholesterol: Excess cholesterol in the blood may develop fatty deposits in blood vessels. Eventually, these deposits make it difficult for adequate blood to flow through the arteries.
Triglycerides: Blood tests for triglycerides are usually part of a lipid profile used to identify the risk of developing heart disease. If you are diabetic, it is especially important to have triglycerides measured as part of any lipid testing since triglycerides increase significantly when blood sugar is out of control.
HDL: HDL is usually ordered with other tests, including cholesterol, LDL, and triglycerides as part of a lipid profile. A complete lipid profile requires fasting for at least 12 hours. If the testing occurs when a person is not fasting, only the HDL and total cholesterol values may be used for risk assessment.
Direct LDL: The test for LDL is used to predict risk of developing heart disease. Of all the forms of cholesterol in the blood, the LDL cholesterol is considered the most important form in determining risk of heart disease.
VLDL (CALC): Very Low Density Lipoprotein is one of three major lipoprotein particles. The other two are high density lipoprotein (HDL) and low density lipoprotein (LDL). Each one of these particles contains a mixture of cholesterol, protein, and triglyceride, but in varying amounts unique to each type of particle. LDL contains the highest amount of cholesterol.
CHOL/ HDL Ratio: The total cholesterol to HDL cholesterol ratio is a number that is helpful in predicting an individual's risk of developing atherosclerosis. The number is obtained by dividing the total cholesterol value by the value of the HDL cholesterol. (High ratios indicate higher risks of heart attacks, low ratios indicate lower risk).
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BONE AND MINERAL SCREEN |
Alkaline Phosphatase: High Alkaline Phosphatase (ALP) usually means that the bone or liver has been damaged. If other liver tests such as bilirubin, AST, or ALT are also high, usually the ALP is coming from the liver. If calcium and phosphate measurements are abnormal, usually the ALP is coming from bone.
Phosphorus: A phosphorus test is often ordered to help diagnose diseases and conditions that cause problems with the body’s utilization of calcium.
Calcium: Although abnormal phosphorus levels usually cause no symptoms, phosphorus testing often is performed as a follow-up to an abnormal calcium level and/or related symptoms, such as fatigue, muscle weakness, cramping, or bone problems.
Calcium (Ionized): Ionized calcium is calcium that is freely flowing in the blood and not attached to proteins. It is also called free calcium. Used as diagnostic marker for kidney or parathyroid disease.
Magnesium: Abnormal levels of magnesium are most frequently seen in conditions or diseases that cause impaired or excessive excretion of magnesium by the kidneys or that cause impaired absorption in the intestines.
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CELIAC/GLUTEN SENSITIVITY SCREEN |
Anti-Gliadin, IgA and IgG: Gliadin IgA and IgG are enzyme-linked immunosorbent assays for the detection of antibodies. Detection of these antibodies is an aid in the diagnosis of certain gluten sensitive enteropathies such as celiac disease and herpetiformis. Celiac disease or gluten sensitivity enteropathy is a chronic condition whose main features include inflammation and characteristic histological “flattening” of intestinal mucosa resulting in a malabsorption syndrome.
Anti-Transglutaminase, IgA: Antibodies to the enzyme tissue transglutaminase (tTG) are found in an overwhelming majority of cases of celiac disease. Tissue transglutaminase modifies gluten peptides into a form that may stimulate the immune system more effectively.
Immunoglobulin (IgA): In order to evaluate how well the mucosal barrier first line immune defense is working, it is necessary to look at total secretory IgA. This measurement is used to further validate the relevance of the salivary IgA result. Suppressed levels of total sIgA may relate to a suppressed IgA anti-gliadin response, even though gluten sensitive enteropathy is present.
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CORONARY RISK SCREEN |
Homocysteine: Homocysteine is an amino acid in the blood. Epidemiological studies have shown that too much homocysteine in the blood (plasma) is related to a higher risk of coronary heart disease, stroke and peripheral vascular disease.
Lipoprotein (a): Lipoproteins are tiny particles that circulate in the blood. They contain cholesterol, fat, and protein in varying amounts depending on the body's need. Lipoprotein (a) is a lipoprotein molecule similar to low density lipoprotein (LDL) cholesterol. Both lipoprotein (a) and LDL are rich in cholesterol and contribute to atherosclerosis of the blood vessels.
CRP (Highly Sensitive): C-reactive protein (CRP) is one of the acute phase proteins that increase during systemic inflammation. It’s been suggested that testing CRP levels in the blood may be an additional way to assess cardiovascular disease risk.
CPK: Creatine phosphokinase is an enzyme found mainly in the heart, brain, and skeletal muscle. All of these areas have elevated serum levels of CPK when stressed, therefore, monitoring the serum level of CPK is important because elevated levels may indicate a serious health disorder, such as heart attack, stroke, or brain tumor.
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GLYCEMIC CONTROL SCREEN |
Cortisol (Serum): Cortisol increases have negative effects over serum blood glucose control and, therefore, insulin levels. It acts as a physiological antagonist to insulin by promoting glycogenolysis (breakdown of glycogen), breakdown of lipids (lipolysis), and proteins, and mobilization of extrahepatic amino acids and ketone bodies. This leads to increased circulating glucose concentrations (in the blood). There is a decreased glycogen formation in the liver.
Glucose: Most of the body’s cells require glucose for energy production; brain and nervous system cells not only rely on glucose for energy, they can only function when glucose levels in the blood remain above a certain level.
Amylase: Amylase is one of several enzymes produced by the pancreas to help digest fats, proteins, and carbohydrates It is secreted through the pancreatic duct into the duodenum, where it helps break down dietary carbohydrates.
Insulin: Insulin is a hormone that is produced and stored in the beta cells of the pancreas. It is vital for the transportation and storage of glucose at the cellular level; it helps regulate blood glucose levels and has a role in lipid metabolism.
Hemoglobin A1c: Measures the amount of glucose chemically attached to red blood cells. Since blood cells live about 3 months, it informs of average glucose for the previous 6 - 8 weeks. A high level suggests poor diabetes control.
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LIVER FUNCTION SCREEN |
Bilirubin, Total: When bilirubin levels are high, jaundice occurs, and further testing is needed to determine the cause. Too much bilirubin may mean that too much is being produced (usually due to increased destruction of red blood cells) or that the liver is incapable of adequately removing bilirubin in a timely manner (due to blockage of bile ducts, liver diseases, or inherited problems with bilirubin handling).
Alkaline Phosphatase: High Alkaline Phosphatase (ALP) usually means that the bone or liver has been damaged. If other liver tests such as bilirubin, AST, or ALT are also high, usually the ALP is coming from the liver. If calcium and phosphate measurements are abnormal, usually the ALP is coming from bone.
SGOT (AST): AST is found in high concentration in heart muscle, liver cells, and skeletal muscle cells. It is also found, to a lesser degree, in other tissues. Although elevated serum AST is not specific for liver disease, it is used primarily to diagnose and monitor the course of liver disease (in combination with other enzymes such as ALT, ALP, and bilirubin).
SGPT (ALT): ALT is measured to see if the liver is damaged or diseased. Low levels of ALT are normally found in the blood. However, when the liver is damaged or diseased, it releases ALT into the bloodstream, which makes ALT levels go up. Most increases in ALT levels are caused by liver damage.
LDH: Lactate dehydrogenase is an enzyme that is found in almost all body tissues but only a small amount of it is usually detectable in the blood. It usually stays contained within the tissues’ cells. When cells are damaged or destroyed, however, they release LDH into the bloodstream, causing blood levels to rise.
GGTP: GGT is an enzyme compared with ALP levels to distinguish between skeletal disease and liver disease. GGT is not increased in bone disorders, as is ALP, so a normal GGT with an elevated ALP would indicate bone disease. And, because the GGT is more specifically related to the liver, an elevated GGT with an elevated ALP may point to liver or bile-duct disease. GGT also has been used as an indicator of heavy and chronic alcohol use.
Total Protein: Total protein measures the combined amount of two classes of proteins, albumin and globulin.
Albumin: Albumin is a carrier of many small molecules, but its main purpose is to keep fluid from leaking out of blood vessels.
Globulin: Globulin proteins include enzymes, antibodies and more than 500 other proteins.
A/G Ratio: The ratio of albumin to globulin (A/G ratio) is calculated from values obtained by direct measurement of total protein and albumin. It represents the relative amounts of albumin and globulins.
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RENAL FUNCTION/ELECTROLYTE SCREEN |
BUN: A blood urea nitrogen (BUN) test measures the amount of nitrogen in the blood that comes from the waste product urea. Urea is formed when protein is broken down in the body. It is produced in the liver and eliminated from the body in urine.
Creatinine: Creatinine is a waste product formed by the breakdown of creatine important for metabolism. The creatinine is filtered out of the blood by the kidneys and then passed out of the body in urine. If the kidneys are damaged and cannot function normally, the amount of creatinine in the urine decreases while the amount of creatinine in the blood increases.
BUN/CREAT Ratio: Found to be predictive of pre-renal renal failure, if the BUN-to-creatinine ratio is greater than 20 or the urea-to-creatinine ratio>0.10 and urea>10. In pre-renal failure, urea rises out of proportion to the creatinine due to enhanced proximal tubular reabsorption.
Uric Acid: The uric acid test is used to learn whether the body might be breaking down cells too quickly or not getting rid of uric acid quickly enough. The test also is used to monitor levels of uric acid when a patient has had chemotherapy or radiation treatments.
Sodium: Blood sodium testing is used to detect hyponatremia (low sodium) or hypernatremia (high sodium) associated with dehydration, edema, and a variety of diseases.
Potassium: To determine if potassium concentration is within normal limits and to help evaluate an electrolyte imbalance; to monitor chronic or acute hyperkalemia (high potassium) or hypokalemia (low potassium).
Chloride: Increased levels of chloride usually indicate dehydration, but can also occur with any other problem that causes high blood sodium. Decreased levels of chloride occur with any disorder that causes low blood sodium.
Carbon Dioxide: When CO2 levels are higher or lower than normal, it suggests that the body is having trouble maintaining its acid-base balance or that electrolyte balance has been upset, perhaps by losing or retaining fluid.
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THYROID SCREEN |
T-3 Uptake: Increased levels are found in hyperthyroidism, severe liver disease, metastatic malignancy, and pulmonary insufficiency. Decreased levels are found in hypothyroidism, normal pregnancy, and hyperestrogenis status.
Total T-4 (Thyroxine): In general, high free or total T4 results may indicate an overactive thyroid gland (hyperthyroidism), and low free or total T4 results may indicate an underactive thyroid gland (hypothyroidism).
Free Thyroxine Index: A mathematical computation allows the lab to estimate the free thyroxine index from the T4 and T3 Uptake tests. The results tell how much thyroid hormone is free in the bloodstream to work on the body.
TSH-Ultra Sensitive: This protein hormone is secreted by the pituitary gland and regulates the thyroid gland. A high level suggests the thyroid is underactive, and a low level suggests the thyroid is overactive.
Free T-3: A T-3 test helps to determine whether the thyroid is functioning properly. It is ordered primarily to help diagnose hyperthyroidism and may be ordered to help monitor the progress of a patient with a known thyroid disorder.
Free T-4: In general, high free or total T-4 results may indicate an overactive thyroid gland (hyperthyroidism), and low free or total T-4 results may indicate an underactive thyroid gland (hypothyroidism).
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