INTERPRETATION OF CBC A complete blood count (CBC) gives important information about the kinds and numbers of cellsin the blood, especially red blood cells, white blood cells, and platelets. A CBC helps your doctor check any symptoms, such as weakness,fatigue, or bruising, you may have. A CBC also helps him or her diagnose conditions, such as anemia, infection, and many other disorders. A CBC test usually includes: White blood cell (WBC, leukocyte) count. White blood cells protect the body against infection. If an infection develops, white blood cells attack and destroy the bacteria, virus, or other organism causing it. White blood cells are bigger than red blood cells but fewer in number. When a person has a bacterial infection, the number of white cells rises very quickly. The number of white blood cells is sometimes used to find an infection or to see how the body is dealing withcancer treatment. White blood cell types (WBC differential). The major types of white blood cells are neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Immature neutrophils, called band neutrophils, are also part of this test. Each type of cell plays a different role in protecting the body. The numbers of each one of these types of white blood cells give important information about the immune system. Too many or too few of the different types of white blood cells can help find an infection, an allergic or toxic reaction to medicines or chemicals, and many conditions, such as leukemia. Red blood cell (RBC) count. Red blood cells carry oxygen from the lungs to the rest of the body. They also carry carbon dioxide back to the lungs so it can be exhaled. If the RBC count is low (anemia), the body may not be getting the oxygen it needs. If the count is too high (a condition called polycythemia), there is a chance that the red blood cells will clump together and block tiny blood vessels (capillaries). This also makes it hard for your red blood cells to carry oxygen. Hematocrit (HCT, packed cell volume, PCV). This test measures the amount of space (volume) red blood cells take up in the blood. The value is given as a percentage of red blood cells in a volume of blood. For example, a hematocrit of 38 means that 38% of the blood's volume is made of red blood cells. Hematocrit and hemoglobin values are the two major tests that show if anemia or polycythemia is present. Hemoglobin (Hgb). The hemoglobin molecule fills up the red blood cells. It carries oxygen and gives the blood cell its red color. The hemoglobin test measures the amount of hemoglobin in blood and is a good measure of the blood's ability to carry oxygen throughout the body. Red blood cell indices. There are three red blood cell indices: mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). They are measured by a machine and their values come from other measurements in a CBC. The MCV shows the size of the red blood cells. The MCH value is the amount of hemoglobin in an average red blood cell. The MCHC measures the concentration of hemoglobin in an average red blood cell. These numbers help in the diagnosis of different types of anemia. Red cell distribution width (RDW) can also be measured which shows if the cells are all the same or different sizes or shapes. Platelet (thrombocyte) count. Platelets (thrombocytes) are the smallest type of blood cell. They are important in blood clotting. When bleeding occurs, the platelets swell, clump together, and form a sticky plug that helps stop the bleeding. If there are too few platelets, uncontrolled bleeding may be a problem. If there are too many platelets, there is a chance of a blood clot forming in a blood vessel. Also, platelets may be involved in hardening of the arteries (atherosclerosis). Mean platelet volume (MPV). Mean platelet volume measures the average amount (volume) of platelets. Mean platelet volume is used along with platelet count to diagnose some diseases. If the platelet count is normal, the mean platelet volume can still be too high or too low. Your doctor may order a blood smear test to be done at the same time as a CBC but it is not part of the regular CBC test. In this test, a drop of blood is spread (smeared) on a slide and stained with a special dye. leukocyte) Conditions that can lower WBC values include chemotherapy and reactions to other medicines. lupus. AIDS. tuberculosis (TB). inflammatory bowel disease. long-term lung disease. some tumors. inflammation. . or surgery). some cancers. white blood cells. thyroid gland problems. Low values Red blood cell (RBC) Anemia lowers RBC values. underactive adrenal glands. kidney failure. Anemia can be caused by heavy menstrual bleeding. alcoholism. Conditions that affect the body's water content can also cause high RBC values. exposure to carbon monoxide. diarrhea or vomiting. injury. such as pernicious anemia. or Cushing's syndrome. and shape of red blood cells. lead poisoning. leukocyte) Conditions that cause high WBC values include infection. malaria. rheumatoid arthritis. which is a problem with absorbing vitamin B12. Platelets High platelet values may be seen with bleeding. damage to body tissues (such as a heart attack). liver disease. The RBC indices value and a blood smear may help find the cause of anemia. A large spleen can lower the WBC count. severe physical or emotional stress (such as a fever. The number. or a rare disorder of hemoglobin that binds oxygen tightly. kidney disease.lupus. sickle cell disease. a rare disorder of the bone marrow (polycythemia vera). size. burns. malaria.Addison's disease. excessive sweating. and platelets are recorded. severe burns. such as leukemia. malnutrition. some diseases like cancer. thalassemia. or reactions to some chemicals and medicines. iron deficiency. A lack of folic acid or vitamin B12 can also cause anemia. this is sometimes called spurious polycythemia. A low RBC value may also be seen if thespleen has been taken out. White blood cell (WBC. viral infections. and diseases such as cancer. These conditions include dehydration. alcoholism.stomach ulcers. Blood cells with different shapes or sizes can help diagnose many blood diseases. leukemia. White blood cell (WBC. A large spleen can lower the platelet count. High values Red blood cell (RBC) Conditions that cause high RBC values include smoking. or removal of the spleen can also cause high WBC values. certain forms of heart disease. or sickle cell disease. colon cancer. The slide is looked at under a microscope. and the use of diuretics. The use of corticosteroids. aplastic anemia. Platelets Low platelet values can occur in pregnancy or idiopathic thrombocytopenic purpura (ITP) and other conditions that affect how platelets are made or that destroy platelets. The lack of fluid in the body makes the RBC volume look high. certain medicines. or problems with the bone marrow. At some stage during the course of renal disease. Altered Laboratory Tests in Renal Disease The kidneys excrete metabolic waste products and regulate the serum concentration of a variety of substances.Interpretation of LFT Interpretation of RFT The kidneys The kidneys regulate the amount of water and salts that we have in our bodies. The kidneys also pass out certain waste products from the body. Urine is made up of the excess water. They do this by filtering the blood through millions of structures called nephrons. salts and waste products passed out by the kidneys down to the bladder. the following routinely . Creatinine is formed spontaneously at a constant rate from creatine. In renal disease with the nephritic syndrome. though not specific. Hyperphosphatemia.measured substances often become abnormal and the extent of the abnormality generally depends on the severity of the disease. Protein in serum can generally be maintained at concentrations above the lower limit of normal by increased hepatic protein synthesis so long as protein loss is less than about 3 g/day. however. hyperuricemia and acidosis (metabolic with an anion gap) do not develop until there is 70-80% loss of functional capacity (i. Urea formation is influenced by a number of factors such as liver function. the urinary protein excretion rate is usually about 1 .. However. Calcium deficiency. The extent of proteinuria also provides useful information. Determination of creatinine clearance. uric acid or bicarbonate.e. measurement of serum phosphate and uric acid is useful for monitoring the effect of therapy during chronic renal disease and/or the effects of attempts to minimize increased serum concentrations by restricting dietary intake of phosphate and nucleotides. unless impairment is rapid (as in acute renal failure) or is sufficiently severe to cause oliguria. does not usually result in frank hypocalcemia because secondary hyperparathyroidism develops as a compensatory response to maintain serum calcium concentrations within the normal range. and is therefore a very sensitive. Excretion rates of creatinine or urea (quantity in urine/day) do not change in renal disease. and so do not provide information about the status of renal function. do not provide a very sensitive indication of the possibility of renal disease. and blood concentrations depend almost solely upon GFR. in the renal failure stage) so that measurements of serum phosphate. urine protein is generally less than 1 g/day. Urea excretion also depends upon hydration status and the extent of water reabsorption as well as upon GFR. from measurement of creatinine concentration in both a 24 hour urine collection and a serum specimen. Bone calcium.4 g/day). Protein in urine is noticeably increased in renal disease of any etiology. Calcium deficiency and consequent osteomalacia is treated with . The greatest degree of proteinuria is found in the nephrotic syndrome ( > 3 . except obstruction. Only in the nephrotic syndrome is the urine protein loss sufficiently great to result in hypoproteinemia. In tubulo-interstitial disease. Acidosis is generally mild and without pathophysiologic consequences until the uremic stage. Serum creatinine and urea concentrations change inversely with changes in GFR and are therefore useful in gauging the degree of renal dysfunction. which occurs during the renal failure stage of chronic renal disease because of deficient renal activation of vitamin D. general screening test for renal disease. provides a clinically useful estimate of GFR. is lost in the process causing renal osteodystrophy which is typically a mild form of osteomalacia and is only rarely the more severe osteitis deformans (Van Ricklenhausen's disease) classically associated with primary hyperparathyroidism. Changes in serum creatinine concentration more reliably reflect changes in GFR than do changes in serum urea concentrations.2 g/day. protein intake and rate of protein catabolism. however. not useful for detecting or assessing the progression of renal disease. so long as intake is not extremely variable. unless renal dysfunction is sufficiently severe to cause oliguria. without hypoxic damage to renal tubule cells despite decreased renal blood flow. However. aldosterone elevation is ineffective in stimulating sodium reabsorption because of tubular damage so that urine sodium concentration is generally at least 25 mEq/L and often greater than 50 mEq/L. aldosterone effectively stimulates sodium reabsorption and urine sodium concentration is generally less than 30 mEq/L.activated vitamin D. serum calcium determinations are not useful for detecting or assessing the severity of renal disease. The fraction of filtered sodium excreted ( FENa) is a more discriminating parameter for evaluating tubular function and is determined by measurement of both serum and urine concentrations of sodium and creatinine: FENa = ( Nau/Nas) / ( Cru/Crs) . Evaluation of renal sodium reabsorption is. Electrolyte determinations are. Sodium and potassium homeostasis is maintained. therefore. but are useful for monitoring the effectiveness of vitamin D therapy and assuring that hypocalcemia is prevented. valuable for assessing tubule function and is useful for distinguishing whether rapidly developing azotemia is due to acute renal failure or to prerenal azotemia from a compensatory decrease in renal blood flow due to hypovolemia. there is considerable overlap in urine sodium concentrations between cases of prerenal azotemia and acute renal failure. In cases of prerenal azotemia. Although calcium metabolism is abnormal. In acute renal failure. Disposable pipets 4.5 mm in internal diameter. Various factors affect the ESR. . The straight tube is 30 cm long.5 ml sodium chloride in puncture ready vials 5. Label the puncture ready vial with the patient’s name. This numeric value is determined (in millimeters) by measuring the distance from the bottom of the surface meniscus to the top of erythrocyte sedimentation in a vertical column containing diluted whole blood that has remained perpendicular to its base for 60 minutes. such as RBC size and shape. and globulin levels. AND EQUIPMENT 1. Westergren rack 3. Westergren tubes 2. In abnormal conditions when RBCs can form rouleaux. SPECIMEN Fresh anticoagulated blood collected in EDTA. In normal whole blood. Remove cap from the puncture ready vial and add well mixed blood up to the line (see illustration). the RBC mass is small and therefore the ESR is decreased (cells settle out slowly). 0. the RBC mass is greater. Timer QUALITY CONTROL Commercial controls are available for this procedure. Hemolyzed specimens cannot be used. PROCEDURE 1. 3. plasma fibrinogen.ERYTHROCYTE SEDIMENTATION RATE PRINCIPLE The erythrocyte sedimentation rate (ESR). SUPPLIES. The Westergren method is preferred by NCCLS standards because of its simplicity and greater distance of sedimentation measured in the longer Westergren tube. The method it replaces is called the Wintrobe method. Approximately 1 mL of blood is required. 2. measures the settling of erythrocytes in diluted human plasma over a specified time period. as well as mechanical and technical factors. The ESR is directly proportional to the RBC mass and inversely proportional to plasma viscosity. REAGENTS. the test must be set up within 6 hours. thus increasing the ESR (cells settle out faster). Leveling plate for holding the Westergren rack 6. and calibrated in millimeters from 0-200. Collect whole blood anticoagulated with EDTA. They will not be used for this exercise. If anticoagulated blood is refrigerated. 2. also called the sed rate. RBCs do not form rouleaux. Blood should be at room temperature and should be no more than 2 hours old. Vibration such as from a nearby centrifuge will cause a false ESR. MLAB 1315 Hematology Replace cap and invert 8 times making sure the blood and saline mix well. less than 6 hours refrigerated. Carefully insert the Westergren tube into plungeable vial cap of blood/diluent mixture twisting as you push the tube down. it is elevated. 6. Set timer for 1 hour. The ESR is elevated in established myocardial infarction but normal in angina pectoris. an angle of even 3 degrees from vertical can accelerate sedimentation by as much as 30%) 7. but not in osteoarthritis. 2.) REPORTING RESULTS Normal values Adult male 0-15 mm/hr Adult female 0-20 mm/hr PROCEDURE NOTES Sources of error 1. Incorrect ratio of blood to diluent 5. Bubbles in the Westergren tube 6. and pyogenic arthritis.must be less than 2 hours at room temperature. rheumatoid arthritis. the ESR is not elevated. Place the tube in the Westergren rack to a vertical position and leave undisturbed for exactly 1 hour. Do not include the buffy coat in this measurement. 7. It is elevated in rheumatic fever. but may be noticeable in cases of leukocytosis or thrombocytosis. the ESR is usually normal. 5. It is usually negligible. After 1 hour has passed. but it may rise later with a superimposed bacterial infection. early in the course of an uncomplicated viral infection.must be between 20-25 C and blood must be at room temperature. 8. read the distance in millimeters from the bottom of the plasma meniscus to the top of the sedimented erythrocytes. temperatuare will cause a false ESR. For example. The ESR can be an index to . Tilting of the Westergren tube (accelerates the fall of the erythrocytes. Within the first 24 hours of acute appendicitis. 3.EXERCISE 1: Erythrocyte Sedimentation Rate 4. 4. Temperature . Age of specimen . (The buffy coat is the layer of white cells and platelets at the interface of red cells and plasma. It can be used to differentiate among diseases with similar symptoms or to monitor the course of an existing disease. but in the early stage of acute pelvic inflammatory disease or ruptured ectopic pregnancy. Usefulness of the ESR The ESR is not a specific test therefore it is used for screening for certain disease conditions. 2. Factors affecting the ESR Increase Rouleaux formation Elevated fibrinogen Excess immunoglobulin Decrease Microcytes Sickle cells Spherocytes . It can therefore be expected that disease states that are characterized by hyperfibrinogenemia or elevated immunoglobulin levels will result in an increased ESR. This is observed with sickle cells and spherocytes. Biological factors affecting the ESR 1. The ESR is of little diagnostic value in severe anemia or in hematologic states evidenced by poikilocytosis.disease severity. Plasma factors Increased plasma concentration of fibrinogen. will result in rouleaux formation and an increased ESR. a decreased or low ESR is expected. RBC factors When rouleaux formation cannot occur. along with immunoglobulin. owing to the shape or size of the RBC.