Total leukocyte count (TLC) means total numbers of leukocyte present in the 1µl undiluted blood. Increase in total leukocyte count of more then 10,000/cu.mm is known as leukocytosis and decrease of less then 4,000/cu.mm as leucopenia.
Causes of Leukocytosis :
- Physiological :
- Age : At birth the total leukocyte count is about 18,000/cu.mm. It drops gradually to adult age.
- Pregnancy : At “full term” the total leukocyte count tends to be about 12,000 to 15,000/cu.mm. Total Leukocyte count is rises soon after delivery and then gradually returns to normal.
- High temperature.
- Sever pain.
- Muscular exercise.
- Pathology :
- Leukocytosis is common for a transient period in infections. The degree of rise in leukocytes depends on the types and severity of the infections and the response of the body. The infection may be bacterial, viral, protozoan, parasitic (filarial, hookworm infection). Leukocytosis is also observed in sever hemorrhage and in leukemia.
Causes of Leucopenia :
Certain viral and bacterial infections leads to leucopenia rather then leukocytosis.
- Infections :
- Bacterial : typhoid, paratyphoid, tuberculosis etc.
- Protozoal : malaria etc.: hepatitis, influenza, measles etc.
- Some cases of Leukaemia.
- Primary bone marrow depression (Aplastic anaemia)
- Secondary bone marrow depression (due to drugs, radiation etc.)
- anaemia : iron deficiency anaemia, Megaloblastic anaemia etc.
Normal values :
- Adults : 4,000 – 11,000 / cu.mm
- At birth : 10,000 – 25,000 / cu.mm
- 1 to 3 years : 6,000 – 18,000 / cu.mm
- 4 to 7 years : 6,000 – 15,000 / cu.mm
- 8 to 12 year : 4,500 – 13,500 / cu.mm
The glacial acidic acid lyses the red cells while the gentian violet slightly stains the nuclei of the leukocytes. The blood specimen is diluted 1 in 20 with the WBC diluting fluid and the cells are counted under low power objective of the microscope by using a counting chamber. The number of cells in undiluted blood is reported as per cu.mm (µl) of whole blood.
- Double Oxalated or EDTA anticoagulated venous blood
- Capillary blood (specimen not be a fasting sample).
- Test tube with test tube rack.
- Improved Neubauer chamber.
- WBC pipette or Micropipette with microtips.
- WBC Diluting fluid
- Glacial acetic acid : 2.0 ml
- 1% Gentian violet : 1.0 ml
- Distilled water : 97.0 ml
- This solution is stable at room temperature (25°C ± 5°C). A pinch of Thymol may be added as a preservative.
- Taken a clean and dry test tube with test tube rack.
- Pipette 380 µl of WBC diluting fluid by using a micropipette with microtips.
- Added 20 µl of well mixed anticoagulated blood and wait for 5 minutes.
- Filled the mixture in the Neubauer counting chamber by the help of micropipette with microtips.
- Counted the number of leukocytes in four specific corner of the Neubauer counting chamber under low power objective (10X) in the microscope.
[Note : For dilution, We also used WBC pipette there blood drawn upto 0.5 mark and afterwards WBC diluting fluid is drawn upto 11 mark and mixed the solution.]