Differential White Cell Count Test

How the Test is Performed

Differential White Cell Count is a blood test performed as a routine part of the Full Blood Count (FBC). It is a blood test.

Medical Conditions and Symptoms

The Differential White Cell Count is part of the routine information provided by a Full Blood Count (FBC), which includes as one of its components the White Cell Count (WCC). Your doctor may pay particular attention to the “Diff count” when there is a suspicion of infection, or when the WCC is particularly high or low – to find out which particular types of white cell are increased or decreased.

Test Results Explained

The Differential White Cell Count is most useful in the setting of a high or low total White Cell Count.
When the WCC is high, the particular proportions of white-cell subtypes may be suggestive of:

• Infection – raised Neutrophils
• Specific infections – raised Lymphocytes may be found in Infectious Mononucleosis, other viral infections, tuberculosis, some fungal infections, or longstanding bacterial infections
• Allergy – raised Eosinophil count

The appearance of the cells under a microscope may also give clues, for example:

• “leftward shift” in neutrophils (appearance of less mature forms) suggests infection, particularly bacterial
• “atypical lymphocytes” suggests Infectious Mononucleosis (glandular fever)
• “blasts” are very immature forms of white cells which suggests (but does not confirm) one of several types of leukaemia

In the setting of a LOW or normal total WCC:

• Low Lymphocyte count suggests viral infection
• Low neutrophil count (neutropaenia) may be due to an acute infection, or may be in the setting of recent chemotherapy, a potentially dangerous situation where the risk of serious infection is increased.

Related Specialists

• General Practitioner (GP)
• Haematologist
• Oncologist
• General Physician
• General Surgeon
• Orthopaedic Surgeon
• Emergency Physician
• Respiratory Physician
• Infectious Disease Physician
• Intensivist
• Paediatrician

Related Procedures

• Blood Test (venesection)
• Bone Marrow Biopsy

Related Tests

• White Cell Count (WCC)
• Full Blood Count (FBC)
• Bacterial Cultures
• Infectious Mononucleosis

Also Known As

• Differential WBC / WCC
• “Diff count”