White blood cells (WBCs) count

There are six types of white blood cells circulates in the blood circulation, which are Neutrophils, lymphocytes, eosinophils, basophils, monocytes and band cells.

White blood cells count is an integral part of complete blood count (CBC), and include two main components:
1- White blood cells count.
2- Differential leucocytes count.

Total white blood cells count:

There are two methods for counting WBCs: 1) Automated method through the electronic blood cells counter. 2) Manual method using the hemocytometer. Electronic counter is more accurate than the hemocytometer method. The electronic counter is expensive, needs periodical maintenance. Maintenance of blood counter is very important; failure to do that will result in misleading results. The hemocytometer method takes longer time, but it is cheaper, which make it suitable for a small laboratory. White blood cells count is expressed in Thousand/cumm, or Giga/liter (G/l).

Differential leucocytic counts (DLC):

Total WBCs count is a measure for the number of all leucocytes in the blood circulation. Total WBCs count alone, can’t be used for interpretation, as it gives no idea about the differential count of the individual cell types. Manual differential leucoytes counts must be done, even if CBC is measured using blood cell counter. DLC is done by spreading of a drop of blood on a glass slide and staining using Giemsa stain, then the blood film is examined under the oil immersion lense. The percent of the individual cells that obtained from the DLC is called the relative number, which is equal to the percent of different leaucocytes from the total leucocytes count. It is not advisable to depend on the relative number in the interpretation of leucocytes count. However, it is better to calculate the absolute number, which is obtained by multiplying the relative number of the individual cells (Percent of cell) by the total leucocytes count.

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