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Company
Complete Blood Count
Review status
Currently under review
Pending specialist review and validation.
This test measures the number of lymphocytes in your blood using an automated analyzer. Lymphocytes are a type of white blood cell that help your immune system recognize and fight infections, as well as respond to vaccines and other immune challenges.
It is usually performed as part of a complete blood count with differential. Automated instruments classify and count cells, providing a direct, absolute lymphocyte count that your clinician interprets alongside other blood cell results and your symptoms.
Your absolute lymphocyte count helps your care team understand how your immune system is functioning. Doctors often order it when you are sick, have swollen lymph nodes, fatigue, fevers, or when monitoring conditions that affect immunity. It is also used to follow people taking medicines that influence the immune system, such as chemotherapy or immunosuppressive drugs.
Counts higher than expected can happen with recent infections or certain blood disorders. Counts lower than expected can occur with some infections, immune deficiencies, medication effects, or bone marrow problems. Tracking the count over time, together with your history and exam, helps guide next steps.
Results are interpreted using age-appropriate reference intervals, because children naturally have different expected values than adults. Your clinician will look at whether your count is higher or lower than usual for you, how rapidly it changed, and how it fits with other parts of your blood count and your symptoms.
If your count is higher than expected, it may reflect a recent or ongoing infection or, less commonly, a lymphoid disorder. Your clinician may recommend repeat testing, a review of your blood smear, or specialized tests if it stays elevated. If your count is lower than expected, common reasons include medication effects, recent illness, or conditions that affect the immune system. Depending on your situation, follow up can include repeating the test after recovery, checking for infections, reviewing medications, or assessing immune function. Do not stop or change any medicines without medical advice.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Viral illnesses and some vaccines can temporarily raise lymphocyte counts as your immune system responds, then return to usual levels as you recover.
Corticosteroids, chemotherapy, certain immunosuppressants, and some biologic therapies can lower lymphocyte counts. Your clinician interprets results in the context of your treatment plan.
Physical or emotional stress and vigorous exercise can shift lymphocytes between the bloodstream and tissues. Modest daily variation also occurs, so timing and recent activity matter.
Delays in processing, clotting, or an underfilled tube can affect automated counts. Laboratories use standardized collection and timing to reduce these issues.
Smoking and heavy alcohol intake can change white blood cell production and distribution, sometimes altering lymphocyte counts over time.
Children normally have higher lymphocyte counts than adults. Pregnancy and chronic illnesses such as autoimmune disease can shift counts and influence interpretation.
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