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Neutrophil-lymphocyte ratio (NLR)
Marker of systemic inflammation and physiological stress from the differential white cell count.
Neutrophil-lymphocyte ratio (NLR)
Absolute neutrophil count
×10⁹/L
Absolute lymphocyte count
×10⁹/L
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When to use
- Gauging the degree of systemic inflammatory or stress response at the bedside from a routine full blood count.
- Tracking trend over time as a low-cost prognostic marker in acute and critical illness.
Formula
NLR = absolute neutrophil count ÷ absolute lymphocyte count. Both counts in the same units (e.g. ×10⁹/L).
Pearls and pitfalls
- A resting NLR is roughly 1–2; values rise within hours of acute physiological stress and fall with recovery.
- Corticosteroids, acute infection and haematological disorders all shift the ratio, so interpret alongside the clinical picture.