Neutrophil-To-Lymphocyte Ratio (NLR)
- Sample Type
- Standard
- Fasting
- No
- Unit
- ratio
NLR is a calculated biomarker derived by dividing the absolute neutrophil count by the absolute lymphocyte count. It serves as a rapid indicator of systemic inflammation and physiological stress. In the context of COVID-19 and other viral pneumonias, a rising NLR is a significant prognostic marker for disease severity, cytokine storm risk, and mortality.
Why Context Matters
NLR is highly sensitive but non-specific. It can be elevated by any form of systemic stress, including steroid administration, recent surgery, or myocardial infarction, which may confound its use as a specific COVID-19 severity marker.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Clinical References
Source-of-truth databases and clinical guidelines for Neutrophil-To-Lymphocyte Ratio (NLR):
Official Sources
- Breast Cancer, Version 3.2024, NCCN Clinical Practice Guidelines in Oncology - PubMedpubmed.ncbi.nlm.nih.gov
- Colon Cancer, Version 3.2024, NCCN Clinical Practice Guidelines in Oncology - PubMedpubmed.ncbi.nlm.nih.gov
Research & Guidelines
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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