Blood Test DefinitionsLaboratory Testing DefinitionsHematologyHEMATOCRIT (HCT)The word hematocrit means "to separate blood", a procedure which is done following the blood draw through the proper use of a centrifuge. Hematocrit is the measurement of the percentage of red blood cells in whole blood. It is an important determinant of anemia (decreased), polycythemia (increased), dehydration (elevated), increased R.B.C. breakdown in the spleen (decreased), or possible overhydration (decreased). Normal Adult Female Range: 37 - 47 % Hemoglobin is the main transport of oxygen and carbon dioxide in the blood. It is composed of globin a group of amino acids that form a protein and heme which contains iron atoms and imparts the red color to hemoglobin. As with Hematocrit, it is an important determinant of anemia (decreased), dehydration (increased), polycythemia (increased), poor diet/nutrition, or possibly a malabsorption problem. Normal Adult Female Range: 12 - 16 % MCH (Mean Corpuscular Hemoglobin) Hemoglobin x 10 / R.B.C. Mean Corpuscular Hemoglobin (MCH) gives the average weight of hemoglobin in the red blood cell. Due to its use of red blood cells in its calculation, MCH is not as accurate as MCHC in its diagnosis of severe anemias. Decreased MCH is associated with microcytic anemia and increased MCH is associated with macrocytic anemia. Normal Adult Range: 27 - 33 pg Hematocrit x 10 / R.B.C. The Mean Corpuscular Volume reflects the size of red blood cells by expressing the volume occupied by a single red blood cell. Increased values may indicate macrocytic anemia or vitamin B6 or Folic Acid deficiency and decreased values may indicate microcytic anemia, possibly caused by iron deficiency. Normal Adult Range: 80 - 100 fL MCHC (Mean Corpuscular Hemoglobin Concentration) Hemoglobin x 100 / Hematocrit This test measures the average concentration of hemoglobin in red blood cells. It is most valuable in evaluating therapy for anemia because Hemoglobin and Hematocrit are used, not R.B.C. in the calculation. Low MCHC means that a unit of packed R.B.C.s contain less hemoglobin than normal and a high MCHC means that there is more hemoglobin in a unit of R.B.C.s. Increased MCHC is seen in spherocytosis, and not seen in pernicious anemia whereas decreased levels may indicate iron deficiency, blood loss, B6 deficiency, or thalassemia. Normal Adult Range: 32 - 36 % Red blood cells main function is to carry oxygen to the tissues and to transfer carbon dioxide to the lungs. This process is possible through the R.B.C. containing hemoglobin which combines easily with oxygen and carbon dioxide. Normal Adult Female Range: 3.9 - 5.2 mill/mcL W.B.C. (White Blood Cell Count) White blood cells main function is to fight infection, defend the body by phagocytosis against invasion by foreign organisms, and to produce, or at least transport and distribute, antibodies in the immune response. There are a number of types of leukocytes (see differential) that are classified as follows:
Each cell, or leukocyte, has a different function in the body which is explained in the Differential section. Normal Adult Range: 3.8 - 10.8 thous/mcL Platelets (also known as thrombocytes) are the smallest formed elements of the blood. They are vital to coagulation of the blood to prevent excessive bleeding. Elevated levels suggest dehydration or stimulation of the bone marrow where the cells are produced and decreased levels may indicate an immune system failure, drug reactions, B12, or folic acid deficiency. Normal Adult Range: 130 - 400 thous/mcL DifferentialNEUTROPHILS and NEUTROPHIL COUNT Also known as Granulocytes or poly-segmented Neutrophils, this is the main defender of the body against infection and antigens. High levels may indicate an active infection, a low count may indicate a compromised immune system or depressed bone marrow (low neutrophil production. Normal Adult Range: 48 - 73 % LYMPHOCYTES and LYMPHOCYTE COUNT Lymphocytes are involved in protection of the body from viral infections such as measles, rubella, chickenpox, or infectious mononucleosis. Elevated levels may indicate an active viral infection and a depressed level may indicate an exhausted immune system or, if the neutrophils are elevated, an active infection. Normal Adult Range: 18 - 48 % These cells are helpful in fighting severe infections and are considered the body's second line of defense against infection and are the largest cells in the blood stream. Elevated levels are seen in tissue breakdown, chronic infections, carcinomas, leukemia (monocytic), or lymphomas. Low levels are indicative of a good state of health. Normal Adult Range: 0 - 9 % EOSINOPHILS and EOSINOPHIL COUNT Eosinophils are used by the body to protect against allergic reactions and parasites. Therefore, elevated levels may indicate an allergic response. A low count is normal. Normal Adult Range: 0 - 5 %BASOPHILS and BASOPHIL COUNT Basophilic activity is not fully understood but it is known to carry histamine, heparin, and serotonin. High levels are found in allergic reactions, low levels are normal. Normal Adult Range: 0 - 2 % ElectrolytesSODIUMSodium is the most abundant cation in the blood and its chief base. It functions in the body to maintain osmotic pressure, acid-base balance, and to transmit nerve impulses. POTASSIUM Potassium is the major intracellular cation in the blood.It, along with sodium, helps to maintain osmotic balance and is also involved in acid-base balance. It is needed forproper nerve and muscle action. CHLORIDE Chloride's significance relates to its maintenance ofcellular integrity through its influence on osmotic pressure, it also helps monitor acid-base balance and water balance. Elevated levels are related to acidosis as well as too much water crossing the cell membrane. Decreased levels with decreased serum albumin may indicate water deficiency crossing the cell membrane (edema). CO2 (Carbon Dioxide) The CO2 level is related to the respiratory exchange of carbon dioxide in the lungs and is part of the body's buffering system. Generally when used with the other electrolytes, it is a good indicator of acidity and alkalinity. CALCIUM The most abundant mineral in the body, it is involved in bone metabolism, protein absorption, fat transfer muscular contraction, transmission of nerve impulses, blood clotting, and cardiac function. It is highly sensitive to elements such as magnesium, iron, and phosphorus as well as hormonal activity, vitamin D levels, alkalinity and acidity, and many drugs. PHOSPHORUS Phosphorus is an abundant element found in most tissues and cells. It is closely related to the calcium level with an inverse relationship. When calcium is increased, phosphorus tends to decrease and vice versa. Careful following of blood draw procedures are necessary because improper handling may cause falsely elevated values. Phosphorus is needed for its buffering action, calcium transport, and osmotic pressure.
Liver EnzymesALKALINE PHOSPHATASEProduced in the cells of the bone and liver with some activity in the kidney, intestine, and placenta. Used extensively as a tumor marker it is also present in bone injury, pregnancy, or skeletal growth (elevated values). Growing children have normally higher levels of this enzyme also. Low levels are sometimes found in hypoadrenia, protein deficiency, malnutrition, and a number of vitamin deficiencies. ALT (ALT Alanine Aminotransferase - sGPT) ALT (Alanine Aminotransferase) or sGPT (serum Glutamic Pyruvic Transaminase) is an enzyme found primarily in the liver but also to a lesser degree, in the heart and other tissues. It is useful in diagnosing liver function more so than sGOT levels. Decreased sGPT in combination with increased cholesterol levels is seen in cases of a congested liver. Increased levels are also seen in mononucleosis, alcoholism, liver damage, kidney infection, chemical pollutants, or myocardial infarction. AST (Aspartate Aminotransferase - sGOT) AST (Aspartate Aminotransferase) or sGOT (serum Glutamic-Oxaloacetic Transaminase) is an enzyme found primarily in the liver, heart, kidney, pancreas, and muscles. Seen in tissue damage, especially heart and liver, this enzyme is normally elevated. Vitamin B deficiency and pregnancy are two instances where the enzyme may be decreased.
GGT (Gamma-Glutamyltransferase or Gamma-Glutamyl Transpeptidase) Believed to be involved in the transport of amino acids and peptides into cells as well as glutathione metabolism, Gamma-Glutamyl Transferase is mainly found in liver cells and as such is extremely sensitive to alcohol use. Elevated levels may be found in liver disease, alcoholism, bile-duct obstruction, cholangitis, drug abuse, and in some cases excessive magnesium ingestion. Decreased levels can be found in hypothyroidism, hypothalamic malfunction, and low levels of magnesium.
LD (Lactic Dehydrogenase - LDH) Lactic dehydrogenase is an intracellular enzyme from particularly in the kidney, heart, skeletal muscle, brain, liver, and lungs. Increases are usually found in cellular death and/or leakage from the cell or, in some cases, it can be useful in confirming myocardial or pulmonary infarction (only in relation to other tests). Decreased levels of the enzyme may be seen in cases of malnutrition, hypoglycemia, adrenal exhaustion, or low tissue or organ activity. BILIRUBIN, TOTAL A byproduct of the breakdown of hemoglobin from red blood cells in the liver, bilirubin is a good indication of the liver's function. Excreted into the bile, bilirubin gives the bile its pigmentation. Elevated in liver disease, mononucleosis, hemolytic anemia, low levels of exposure to the sun, and toxic effects to some drugs, decreased levels are seen in people with an inefficient liver, excessive fat digestion, and possibly a diet low in nitrogen bearing foods.
Nitrogen ElementsB.U.N. (Blood Urea Nitrogen)The nitrogen component of urea, B.U.N. is the end product of protein metabolism and its concentration is influenced by the rate of excretion. Increases can be caused by excessive protein intake, kidney damage, certain drugs, low fluid intake, intestinal bleeding, exercise, or heart failure. Decreased levels may be due to a poor diet, malabsorption, liver damage, or low nitrogen intake. CREATININE Creatinine is the waste product of muscle metabolism. Its level is a reflection of the body's muscle mass. Low levels are sometimes seen in kidney damage, protein starvation, liver disease, or pregnancy. Elevated levels are sometimes seen in kidney disease due to the kidneys job of excreting creatinine, muscle degeneration, and some drugs involved in impairment of kidney function. URIC ACID Uric acid is the end product of purine metabolism and is normally excreted through the urine. High levels are noted in gout, infections, kidney disease, alcoholism, high protein diets, and with toxemia in pregnancy. Low levels may be indicative of malabsorption, a diet low in purines, liver damage, or an overly acid kidney.
ProteinPROTEIN, TOTALProteins are the most abundant compound in serum. The protein makeup of the individual is of important diagnostic significance because of protein's involvement in enzymes, hormones, and antibodies as well as osmotic pressure balance, maintaining acid-base balance, and as a reserve source of nutrition for the body's tissues and muscles. The major serum proteins measured are Albumin and Globulin (alpha1, alpha2, beta, and gamma). Decreased levels may be due to poor nutrition, liver disease, malabsorption, diarrhea, or severe burns. Increased levels are seen in lupus, liver disease, chronic infections, alcoholism, leukemia, tuberculosis amongst many others. Careful review of the individuals albumin, globulin, and A/G ratio are recommended. ALBUMIN Albumin is the major constituent of serum protein (usually over 50%). It is manufactured by the liver from the amino acids taken from the diet. It helps in osmotic pressure regulation, nutrient transport, and waste removal. High levels are rarely seen and are primarily due to dehydration. Low levels are seen in poor diets, diarrhea, fever, infection, liver disease, inadequate iron intake, third-degree burns and edemas, and hypocalcemia. GLOBULIN Globulin, a larger protein than albumin, is important for its immunologic responses, especially its gamma component (IgA, IgG, IgM, and IgE). Globulins have many diverse functions such as, the carrier of some hormones, lipids, metals, and antibodies. When chronic infections, liver disease, rheumatoid arthritis, myelomas, and lupus are present, elevated levels are seen. Lower levels may be found in immune compromised patients, poor dietary habits, malabsorption, and liver or kidney disease. A/G RATIO (Albumin/Globulin Ratio) A/G ratio is an important indicator of disease states although a high level is not considered clinically significant.
LipidsCHOLESTEROLCholesterol is a critical fat that is a structural component of cell membrane and plasma lipoproteins, and is important in the synthesis of steroid hormones, glucocorticoids, and bile acids. Mostly synthesized in the liver, some is absorbed through the diet, especially one high in saturated fats. High density lipoproteins (HDL) is desired as opposed to the low density lipoproteins (LDL), two types of cholesterol. Elevated cholesterol has been seen in artherosclerosis, diabetes, hypothyroidism, and pregnancy. Low levels are seen in depression, malnutrition, liver insufficiency, malignancies, anemia, and infection. TRIGLYCERIDES Triglycerides, stored in adipose tissues as glycerol, fatty acids, and monoglycerides, are reconverted as triglycerides by the liver. Ninety percent of the dietary intake and 95% of the fat stored in tissues are triglycerides. Increased levels may be present in artherosclerosis, hypothyroidism, liver disease, pancreatitis, myocardial infarction, metabolic disorders, toxemia, and nephrotic syndrome. Decreased levels may be present in chronic obstructive pulmonary disease, brain infarction, hyperthyroidism, malnutrition, and malabsorption. LDL (Low Density Lipoprotein) LDL is the cholesterol rich remnants of the lipid transport vehicle VLDL (very-low density lipoproteins) there have been many studies to correlate the association between high levels of LDL and arterial artherosclerosis. Due to the expense of direct measurement of LDL a calculation, known as the Friedewald formula is used. It is Total Cholesterol - HDL Cholesterol - (Triglycerides/5). When triglyceride levels are greater than 400 mg/dL, this calculation is not accurate. HDL (High Density Lipoprotein) HDL or High-density lipoprotein is the cholesterol carried by the alpha lipoproteins. A high level of HDL is an indication of a healthy metabolic system if there is no sign of liver disease or intoxication. The two mechanisms that explain how HDL offers protection against chronic heart disease are that 1. HDL inhibits cellular uptake of LDL and 2. serves as a carrier that removes cholesterol from the peripheral tissues and transports it back to the liver for catabolism and excretion. CHOLESTEROL/LDL RATIO The ratio of total cholesterol and LDL (low density lipoprotein).
RatiosANION GAP (Sodium + Potassium - CO2 - Chloride)The anion gap is used to measure the concentration of cations (sodium and potassium) and the anions (chloride and CO2) in the extracellular fluid of the blood. There are numerous clinical implications that can be gathered from the Anion Gap. An increased measurement is associated with metabolic acidosis due to the overproduction of acids (a state of alkalinity is in effect). Decreased levels may indicate metabolic alkalosis due to the overproduction of alkaloids (a state of acidosis is in effect). B.U.N./CREATININE A high value in this calculation is normally indicative of too much B.U.N. being formed and a low value may show that the B.U.N. is low or that the creatinine is not being cleared effectively by the kidney. This calculation is a good measurement of kidney and liver function. CALCIUM/PHOSPHORUS Due to the delicate balance between calcium and phosphorus in the system, this calculation is helpful in noting subtle and acute imbalances in the relationship between the two elements. SODIUM/POTASSIUM As the two major blood electrolytes, sodium as the extracellular cation and potassium as the intracellular cation, this is an important ratio to review and act upon when subtle or acute imbalances are noted.
ThyroidTHYROXINE (T4)Thyroxine is the thyroid hormone that contains four atoms of iodine. It is used to evaluate thyroid function. It is the direct measurement of total T4 concentration in the bloodserum. Increased levels are found in hyperthyroidism, acute thyroiditis, and hepatitis. Low levels can be found in Cretinism, hypothyroidism, cirrhosis, malnutrition, and chronic thyroiditis. T-UPTAKE (T3-Uptake) This test is an indirect measurement of unsaturated thyroxine binding globulin in the blood. 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. FREE T4 INDEX (T7) This index is a calculation used to correct the estimated total thyroxine for the amount of thyroxine binding globulin present. It uses the T4 value and the T-uptake ratio. THYROID STIMULATING HORMONE (TSH) TSH, produced by the anterior pituitary gland, causes the release and distribution of stored thyroid hormones. When T4 and T3 are too high, TSH secretion decreases, when T4 and T3 are low, TSH secretion increases.
OtherGLUCOSE (Fasting)Glucose, formed by the digestion of carbohydrates and the conversion of glycogen by the liver, is the primary source of energy for most cells. It is regulated by insulin, glucagon, thyroid hormone, liver enzymes, and adrenal hormones. It is elevated in diabetes, liver disease, obesity, pancreatitis, due to steroid medications, or during stress. Low levels may be indicative of liver disease, overproduction of insulin, hypothyroidism, or alcoholism. IRON, TOTAL Iron is necessary for the formation of some proteins, hemoglobin, myoglobin, and cytochrome. Also, it is necessary for oxygen transport, cellular respiration, and peroxide deactivation. Low levels are seen in many anemias, copper deficiencies, low vitamin C intake, liver disease, chronic infections, high calcium intake, and women with heavy menstrual flows. High levels are seen in hemochromatosis, liver damage, pernicious anemia, and hemolytic anemia.
A useful glossary of medical and scientific terms: http://lpi.orst.edu/infocenter/glossary.html#H.
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