Neutrophils
Immune system healthAlso known as: NEU, polymorphonuclear leukocytes, polys, PMN
Neutrophils (primary bacterial fighters) respond rapidly to acute infections.
Reference range
Source: lab benchmark
Reference ranges may vary between labs and assays. Always interpret results with your healthcare provider.
Why this matters
Neutrophil levels provide an early indication of immune system strength. Low neutrophils, or neutropenia, greatly increase infection risk, making even minor infections potentially serious, while high neutrophils usually indicate an active bacterial infection or inflammation. Supporting immune health through adequate sleep, balanced nutrition, stress management, and regular exercise helps maintain healthy neutrophil levels and effective infection defense.
How this connects to other biomarkers
- Elevated Neutrophil percentage with elevated total Leukocytes and high hs-CRP is the classic pattern of bacterial infection or acute inflammation.
- A high NLR (Neutrophils/Lymphocytes) ratio (Neutrophils divided by Lymphocytes) > 3 is a non-specific marker of physiologic stress and is associated with worse outcomes in cardiovascular disease, cancer, and infection.
- Low neutrophil percentage with a normal absolute count usually reflects relative lymphocytosis rather than true neutropenia — confirm with Neutrophils (abs.).
How often should I test Neutrophils?
Most adults benefit from yearly neutrophil percentage testing as part of a CBC differential. Persistent or significant abnormalities prompt your clinician's follow-up rather than a fixed retest cadence.
At baseline / for screening: Once every 12 months from age 30 as part of a CBC with differential.
Note: Acute infection raises neutrophils within hours; intense exercise within minutes. Wait 2 to 4 weeks after acute illness for a stable baseline, and avoid intense exercise in the 24 to 48 hours before testing.
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