Lymphocytes (abs.)
Immune system healthThe absolute count of lymphocytes per liter of blood.
Lymphocytes include T cells and B cells — the cornerstone of adaptive immunity — as well as natural killer (NK) cells, which provide innate immune defense. The absolute count is critical for assessing immune competence, as a normal percentage can hide true lymphopenia when total white blood cells are low.
Reference range
Female
Source: lab benchmark
Male
Source: lab benchmark
Reference ranges may vary between labs and assays. Always interpret results with your healthcare provider.
Why this matters
Low lymphocytes increase susceptibility to viral infections, recurring thrush, and unusual infections like pneumocystis pneumonia. You might experience frequent cold sores, shingles reactivation, or persistent warts. High lymphocytes often indicate viral infections (with fever, fatigue, sore throat, swollen glands) or chronic conditions. Very high counts could suggest lymphoma or leukemia with symptoms including painless swollen lymph nodes, night sweats, unexplained weight loss, and persistent fatigue.
How this connects to other biomarkers
- Lymphocytopenia (< 1 × 10⁹/L) is associated with HIV (check HIV screening), corticosteroid therapy, severe sepsis, COVID-19, and lymphoma; severe persistent lymphopenia warrants HIV testing and CD4 count.
- Lymphocytosis (> 4 × 10⁹/L) is common in viral infections; in older patients, persistent lymphocytosis with abnormal smear morphology should prompt evaluation for chronic lymphocytic leukemia (CLL).
- The NLR (Neutrophils/Lymphocytes) ratio is a key composite marker that uses lymphocyte count.
Included in
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