Blood count
White Blood Cells
LOINC 6690-2 · /uL
Ranges
Reference range: 4500–11000 /uL
What it is
The white blood cell (WBC) count is the total number of immune cells in your blood that defend against infection.
Why it matters
It is a broad indicator of infection, inflammation and immune-system health.
What high values can mean
A higher count commonly reflects infection, inflammation, stress or, less often, a marrow condition.
What low values can mean
A lower count can follow some viral infections, medications or marrow problems and may raise infection risk.
How to improve it
Counts usually return to normal as an infection or stressor resolves; persistent changes need a cause found.
Food & lifestyle
Good sleep, balanced nutrition and not smoking support healthy immune function.
Preparing for the test
Part of a complete blood count (CBC); fasting is not required.
When to talk to a doctor
Discuss a markedly high or low WBC count with a doctor, interpreted with the differential.
Related markers
Sources
- MedlinePlus (NIH)
- Testing.com (AACC)
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
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