Lymphocytes (count and %) is a blood test that measures lymphocytes (count and %) levels in the blood. Normal range: Lymphocytes are typically about 1.0-4.0 x10^9/L in adults (children normally run higher). They are the main drivers of the immune response, so their count shifts predictably with infections.. It is commonly used to helps evaluate immune function and detect viral infections, lymphoma, and leukemia..
What is Lymphocytes (count and %)?
White blood cells that play a central role in immune responses.
Why is it measured?
Helps evaluate immune function and detect viral infections, lymphoma, and leukemia.
Normal Reference Range
Lymphocytes are typically about 1.0-4.0 x10^9/L in adults (children normally run higher). They are the main drivers of the immune response, so their count shifts predictably with infections.
Note: Reference ranges may vary between laboratories. Always consult your healthcare provider for interpretation.
What Causes High LYMPHOCYTES?
A high lymphocyte count (lymphocytosis) is most commonly caused by viral infections — including glandular fever (Epstein-Barr virus), which produces characteristic atypical lymphocytes — and whooping cough. A transient rise can follow physical stress. A persistently high count, especially in older adults, can indicate chronic lymphocytic leukaemia or lymphoma and is followed up with a blood film and flow cytometry.
What Causes Low LYMPHOCYTES?
A low lymphocyte count (lymphopenia) is seen during acute infections and sepsis, and is a recognised feature of severe viral illness including COVID-19. Other causes include corticosteroid and chemotherapy treatment, autoimmune disease, HIV infection, and malnutrition. Persistent unexplained lymphopenia warrants assessment of immune function.
How Often Should LYMPHOCYTES Be Tested?
Lymphocytes are reported in the differential of every full blood count. A mildly raised count with an obvious viral illness usually needs no action; a persistent or marked abnormality is investigated with a blood film and, if needed, specialised tests.
Related Blood Markers
Lymphocytes are interpreted with the rest of the differential — neutrophils, monocytes, eosinophils, basophils — and the total white cell count. A blood film and flow cytometry characterise persistent abnormalities.
Key Facts
- •Category: Blood Health
- •Unit of Measurement: 10^9/L
- •Test Code: LYMPHOCYTES
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