Lymphocytosis (high lymphocyte count)
By Mayo Clinic staffOriginal Article: http://www.mayoclinic.com/health/lymphocytosis/MY00360
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Definition
Lymphocytosis (lim-foe-sie-TOE-sus), or high lymphocyte count, is an increase in white blood cells called lymphocytes (LIM-foe-sites). There are five primary subtypes of white blood cells, each with a different disease-fighting activity.
A count of more than 2,900 lymphocytes in a microliter of blood is generally considered to be lymphocytosis in adults. However, the threshold for lymphocytosis varies from one medical practice to another. In children, the threshold for lymphocytosis varies with age.
Causes
You may have a lymphocyte count that exceeds the typical threshold but have no disease present. Your doctor makes a judgment about whether the count is "too high" based on other factors, such as symptoms you may be experiencing and the results of other tests.
If your doctor determines your lymphocyte count is high, the test result may be evidence of one of the following conditions:
- Infection (bacterial, viral, other)
- Cancer of the blood or lymphatic system
- An autoimmune disorder causing ongoing (chronic) inflammation
Specific causes of lymphocytosis include:
When to see a doctor
A high lymphocyte count is usually found when your doctor has ordered tests to help diagnose a condition you're already experiencing. It's rarely an unexpected finding or simply discovered by chance. Talk to your doctor about what your test results mean. A high lymphocyte count and results from other tests may already indicate the cause of your illness, or your doctor may suggest other tests to further assess your condition.
- Laboratory reference values. Hematology group (Lymphocyte). Rochester, Minn.: Mayo Foundation for Medical Education and Research; Nov. 2010.
- Hematology. In: Wallach J. Interpretation of Diagnostic Tests. 8th ed. Philadelphia, Pa.: Wolters Kluwer Health Lippincott Williams & Wilkins; 2007. http://gateway.ovid.com/ovidweb.cgi?T=JS&MODE=ovid&PAGE=main&D=baov&PCOSTART=wallach. Accessed Nov. 29, 2010.
- Wilkinson JM (expert opinion). Mayo Clinic, Rochester, Minn. Dec. 6, 2010.
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