Hematology functions tests (Physio).pdf

Hematology functions tests Prepared and presented by: Dr.Hanan Essam  Objectives 1) Discuss ESR and its clinical significance. 2) Discuss Hematocrit value and its clinical significance. 3) Interpret Complete Blood picture (CBC) and its clinical significance. 4) Discuss Osmotic f...

Hematology functions tests Prepared and presented by: Dr.Hanan Essam  Objectives 1) Discuss ESR and its clinical significance. 2) Discuss Hematocrit value and its clinical significance. 3) Interpret Complete Blood picture (CBC) and its clinical significance. 4) Discuss Osmotic fragility test and its clinical significance. 1- Erythrocyte sedimentation rate (ESR) Definition: It is the rate by which the red cells sediment when blood is placed vertically in a narrow tube.  Westergren Apparatus: Westergren Tube (Calibration: 0- 200 mm from above to downward). Stand.  Principle: When a sample of blood is placed in a tube, the red blood cells normally settle out relatively slowly (As RBCs normally are –ve charge so there are repulsion between them) , leaving little clear plasma. The red cells settle at a faster rate in the presence of an increased level of proteins, particularly proteins called immunoglobulins which neutralize the – ve charge of RBCs leading to increase attraction between RBCs and increase the sedimentation rate (Rouleaux phenomena).  Leave the pipette for one hour & then read the height (in mm) of the column of clear plasma above the precipitated RBCs. 1 hour ESR can be calculated after 2 hours using the following equation: Reading of 1st hour + ½ reading of 2nd hour 2 5  Normal values: Males: 4-6 mm/h up to 15 mm/h. Female: 8-10 mm/h up to 20 mm/h ( As red cell count in females is lower ). Clinical significance (Prognostic not diagnostic): ESR test is not-specific and not diagnostic test, as it only confirms the presence or absence of inflammatory activity in the body and to monitors it is progressing or responding to treatment. It increases physiological in Female during pregnancy, menstruation & lactation. It increase in pathological conditions such as :Tonsillitis, fractures, myocardial infarction and rheumatoid arthritis. 2-Packed cell volume (PCV) Hematocrit value (Hct V) Definition: The percentage of the blood volume that is made up of red blood cells. Methods for detection: 1- Macro hematocrit method: We use Wintrobe hematocrit tube. After completion of the centrifugation, the tube is taken out, and RBC column height is reported as HCT. 2-Micro hematocrit method: We use heparinized microhaematocrit capillary tube. After completion of the centrifugation, place the lower end of the tube along the zero line of the hematocrit reader. Move the tube along those lines until the top of the plasma intersects the top line of the hematocrit reader. The value of the hematocrit is read on the top of RBCs column.  Clinical significance: Normal Values: Male: Average 42-52 % Female: Average 37-47 % Dehydration Increase PCV: Polycythemia Over hydration Decrease PCV Anemia 3- Complete blood picture (CBC) The complete blood count is the calculation of the cellular elements of blood. The automated hematology analyzer that analyze the different components of blood in less than a minute generally determine these calculations. It is used to determine your general health status; to screen for, diagnose, or monitor any one of a variety of diseases and conditions that affect blood cells, such as anemia(Decrease Hb) , infection& inflammation (Increase WBCs level), bleeding disorder (Decrease platelets number or abnormal function)  The calculation of Red Blood Indices 1. Mean cell volume (MCV): The average volume of red blood cell measured by femtoliters (fl) MCV = PCV x 10 RBC count 2. Mean cell hemoglobin (MCH): The average amount of Hb in a single red blood cell measured by picogram (pg) MCH = Hb x 10 RBC count. 3. Mean cell Hb concentration (MCHC): Concentration of Hb per 100 ml of RBC measured in g/dl MCHC = Hb x 100 PCV 4-Osmotic Fragility Test It is used to measure erythrocyte resistance to hemolysis while being exposed to varying levels of dilution of a saline solution. The sooner hemolysis occurs, the greater the osmotic fragility of the cells. The biconcave shape of RBCs allows 45-65% increases in their volume before they rupture. This range indicates that RBCs vary in their fragility because the older cells are more fragile and rupture before the younger ones  Procedure: A series of test tubes containing 2ml of decreasing concentrations of NaCl starting from isotonic 0.9%NaCl and gradually decreasing conc. until 0.0% NaCl (D.W). 0.1 ml blood is added to each tube. Allow to stand in a rack for 1 hour. Observe the fluid color and RBCs precipitate. Detect: a- The conc. where hemolysis first started (Partial hemolysis). b- The conc. where hemolysis was first completed (Complete hemolysis).  Clinical significance: Enzymatic deficiency (G- 6-P-D Increased fragility: deficiency) Hereditary spherocytosis Iron deficiency anemia: The red Decreased fragility cells are flattened but they not fragile. Thalassemia. Sickle cell anemia  Reference Guyton and Hall Textbook of Medical Physiology (Guyton physiology) 14th edition. A Textbook Of Practical Physiology , Eighth edition.CL Ghai MBBS MD.