Lymphocytes
Also written as: lymphs, absolute lymphocyte count
The white blood cells behind targeted immunity - T cells, B cells, and natural killer cells.
What it measures
The number of lymphocytes in the blood, reported as an absolute count and as a percentage of white cells. Lymphocytes include T cells, B cells, and natural killer cells - the cells that mount targeted immune responses and carry immune memory.
Why a doctor orders it
It comes with every complete blood count with differential. Clinicians pay attention to it during and after infections, when evaluating immune conditions, and while monitoring certain medications.
What is generally associated with a higher result
Broadly associated with certain infections known for raising lymphocytes - infectious mononucleosis and whooping cough are the classic examples - and with recovery after an illness. Many everyday viral illnesses temporarily lower lymphocytes instead, so the direction alone says little. Children normally run higher counts than adults. A persistent, unexplained elevation is what prompts further evaluation rather than a single high reading.
What is generally associated with a lower result
Broadly associated with acute stress or acute illness, corticosteroid medicines, and some immune conditions. A temporary dip during and shortly after a common infection is frequent and usually resolves on its own.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- A recent or current viral illness, even a mild one
- Corticosteroid medicines, which lower the count temporarily
- Intense exercise shortly before the draw
- Physical or emotional stress
- Time of day
Questions to take to your appointment
- Could a recent cold or other infection explain the change?
- Is the shift in the absolute count, or only in the percentage?
- If it stayed shifted once I have been well for a while, what would you look at next?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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