What it measures
Lymphocytes are white blood cells that include B cells, which make antibodies, and T cells, which attack infected cells and direct other immune cells. The count is part of the white cell breakdown (the differential) in a full blood count.
Why people test it
- Reported with a full blood count that includes the white cell breakdown.
- Often rises during viral infections such as glandular fever.
- Can fall with steroid medicines, some other medicines and severe illness.
- A raised count that stays raised is looked into with a blood film.
Typical range
Ranges vary by lab and method, and counts are naturally higher in children. Your report shows the lab's own range.
Finger-prick or vein?
A vein sample is usually advised. Blood from a finger prick can clot or break up (haemolyse) in the tube, which upsets blood-count results.