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Differential Leukocyte Count

The differential leucocyte count or DLC is a relative proportion of different types of WBCs (leucocytes) expressed as percentages. There are five types of WBC cells (leukocytes) i.e., Neutrophils, Eosinophils, Basophils, Monocytes, and Lymphocytes.

When we calculate the percentage of these individual types of cells in whole WBC in relation to each other, this process is called DLC or Differential leukocyte count.

A blood sample of a person is used to find out the DLC of his WBC cells. If the percentage of any individual type of WBC cells is lower or higher than the normal range, this can indicate an infection.

The Normal Range of DLC is as follows (in Percentage)

  • Neutrophils: 40 – 70%
  • Lymphocyte: 15 – 40%
  • Monocyte: 2 – 10%
  • Eosinophils: 1 – 6%
  • Basophils: 0 – 2%

The normal range of DLC per cubic millimetre

  • Neutrophils: 2500 – 8000/mm3
  • Lymphocyte: 1000 – 4000/mm3
  • Monocyte: 100 – 700/mm3
  • Eosinophils: 50 – 500/mm3
  • Basophils: 25 – 100/mm3

The increased or decreased number of any type of leucocyte can be an indication of an infection, allergy, or symptoms of any specific disease. Here are some examples…

Neutrophilia:

The increased number of Neutrophils called neutrophilia that is an indication of bacterial infection like pneumonia, abscesses, meningitis, UTI, etc.

Neutropenia:

The decreased number of Neutrophils called neutropenia is an indication of anaemia, aplastic anaemia, aleukemic leukaemia.

Eosinophilia:

The increased number of eosinophils called eosinophilia indicates Parasitic infection, Allergic infection, Asthma, Rhinitis, Urticaria, Eczema, Dermatitis, etc.

Basophilia:

The increased number of basophils called basophilia is an indication of acute allergic infection, an immediate type of hypersensitivity.

Monocytosis:

The increased number of monocytes called monocytosis is an indication of chronic infection like Tuberculosis (TB).

Lymphocytosis:

The increased number of lymphocytes called lymphocytosis is an indication of viral infection and chronic infection.