Total WBC Count Test PDF

Total WBC Count Test By: Assistant Lecturer Halah H. Ali Introduction The white blood cell (WBCs; leukocytes) count denotes the number of white blood cells per unit volume of whole blood. Normal WBC count range from 4000-11000 cell/μL. this count varies with age. WBC count is useful to indicate infe...

Total WBC Count Test By: Assistant Lecturer Halah H. Ali Introduction The white blood cell (WBCs; leukocytes) count denotes the number of white blood cells per unit volume of whole blood. Normal WBC count range from 4000-11000 cell/μL. this count varies with age. WBC count is useful to indicate infection or employed to follow progress of certain disease. WBC in circulation are not white in sense, but they are transparent. White cells are fewer in number than red cells. Abnormal Results A high white blood cell count, called leukocytosis (an increase in the number of WBCs beyond 11,000/μL), may result from a number of conditions including: - Infections. -Inflammation such as rheumatoid arthritis and inflammatory bowel disease. -Tissue death such as trauma, burns, surgery or heart attack. - Allergic responses. - Malignancies. Abnormal Results A low white blood cell count, called leukopenia, it is below 4,000 /μL can result from conditions such as: -Primary bone marrow disorders: the bone marrow does not produce sufficient WBCs (e.g. aplastic anemia). - Bone marrow damage caused by: toxin, chemotherapy, radiation. - Autoimmune (e.g., Systemic lupus erythematosus). - Iron deficiency anemia. - Deficiency of vitamin such as: B12 or folate. Principle A sample of blood is diluted with a special type of dilution fluid (Turk 's solution) which destroys red cells and stains the nuclei of the leukocytes. Turk 's solution composed of: Glacial acetic acid, gention violet and water. Materials Fresh blood EDTA Tubes WBCs diluting Turk’s solution. Neubauer slide (Haemocytometer) Coverslips Microscope Procedure Preparation: 1. Draw (20 μL) of blood sample and put in EDTA tube. 2. Add 400 μL of WBCs diluting fluid (to make a dilution of 20 times). 3. Mix fluid and blood in a test tube and leave for 3 minutes. 4. Place coverslip in position over ruled area of the chamber. Procedure Application: 1. Draw small volume of the diluted blood and fill the Neubauer chamber. 2. Make sure that the chamber is free of air bubbles. 3. The distribution of the cells should be uniform over the ruled area. 4. Allow for 2 minutes to settle the cells. Procedure Counting: 1. Now count WBCs in the Neubauer chamber. 2. Use the microscope (10 X) to count the WBCs. 3. For WBCs, use the 4 corner square. 4. Count WBCs within the 16 small squares in each corner square. 5. Count only the WBCs that fall on these squares, left and top borders. 6. The WBCs look like black dots. Calculation Formula for Total WBC Count is: Total WBCs count/ mm3 = No. of WBCs x multiply factor Multiply factor= dilution factor/ volume of fluid inside chamber Volume of fluid inside chamber = Area x Depth Calculation Area: Each large corner square has dimensions= 1 mm x 1 mm= 1 mm2 Area of 4 corner squares= 4 mm2 Depth: Depth of chamber = 0.1 mm Then: Volume = Area ×Depth= 4 x 0.1 = 0.4 mm3 Multiply factor= dilution factor/ volume of fluid inside chamber= 20/0.4 = 50 Calculation Example-1: The sum of the cells counted in the four corner areas= 140. Calculate total WBC count per liter. Total WBCs count/ mm3 = No. of WBCs x multiply factor = 140 cell × 50= 7000 cell/ mm3 = 7000 cell × 10 6 = 7 × 109 cell/ L Calculation Example-2: If 200 cells were seen in the four large corner squares. Calculate total WBC count per liter. Total WBCs count/ mm3 = No. of WBCs x multiply factor = 200 cell × 50= 10000 cell/ mm3 = 10000 cell × 10 6 = 10 × 109 cell/ L