Biomarker · Blood count
White blood cell count (WBC)
White blood cells are part of the immune system. What the WBC count and differential show, and common reasons a count may be higher or lower.
Written by LON6EVITY Editorial Team · Last updated
What it measures
A white blood count measures the number of white blood cells, which help the body fight infection. A differential breaks the count into the main types, such as neutrophils and lymphocytes.
Why counts change
MedlinePlus notes that a high count may be due to infection, inflammation, some medicines, stress or, less commonly, blood disorders. A low count may be caused by some medicines, autoimmune conditions, bone marrow problems or certain infections.
Context matters
Short-term changes are common, for example during an infection. Clinicians look at the differential, other blood count values and symptoms before drawing conclusions.
Reference ranges
Reference ranges differ between laboratories, units and methods, and depend on age, sex and your overall clinical picture. A single result is not a diagnosis — interpret it with a qualified clinician.
Factors that can affect the result
- Infection
- Inflammation
- Medicines
- Stress
- Smoking
Questions people commonly ask
- Is a slightly high WBC a concern?
- Often it reflects a recent infection or other temporary cause. A clinician may repeat the test.
Related biomarkers
Related tests
Understand your biomarkers in context
What does this mean for your own health data? Log your results, follow trends over time and bring an organised summary to your next doctor's appointment.
Sources
- White Blood Count (WBC). MedlinePlus, U.S. National Library of Medicine.
- Complete Blood Count (CBC). MedlinePlus, U.S. National Library of Medicine.