Causes

By Mayo Clinic Staff

It's possible to have a higher than usual lymphocyte count but have few, if any, symptoms. The higher count usually comes after an illness. It is most often harmless and doesn't last long.

But the higher count might be the result of something more serious, such as a blood cancer or a chronic infection. More tests can show if the lymphocyte count is a cause for worry.

A high lymphocyte count can point to:

  1. Infection, including bacterial, viral or other type of infection.
  2. Cancer of the blood or lymphatic system.
  3. An autoimmune disease causing ongoing, called chronic, swelling and irritation, called inflammation.

Causes of lymphocytosis include:

  1. Acute lymphocytic leukemia
  2. Babesiosis
  3. Brucellosis
  4. Cat-scratch disease
  5. Chronic lymphocytic leukemia
  6. Cytomegalovirus (CMV) infection
  7. Hepatitis A
  8. Hepatitis B
  9. Hepatitis C
  10. HIV/AIDS
  11. Hypothyroidism (underactive thyroid)
  12. Lymphoma
  13. Mononucleosis
  14. Severe medical stress, such as from trauma
  15. Smoking
  16. Splenectomy
  17. Syphilis
  18. Toxoplasmosis
  19. Tuberculosis
  20. Whooping cough

Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.

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Aug. 31, 2023