You can have a higher than normal lymphocyte count but have few, if any, symptoms. It usually occurs after an illness and is harmless and temporary.
But it might represent something more serious, such as a blood cancer or a chronic infection. Your doctor might perform other tests to determine if your lymphocyte count is a cause for concern.
If your doctor determines that your lymphocyte count is high, the test result might 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:
- Acute lymphocytic leukemia
- Chronic lymphocytic leukemia
- Cytomegalovirus (CMV) infection
- Hepatitis A
- Hepatitis B
- Hepatitis C
- Hypothyroidism (underactive thyroid) (underactive thyroid)
- Other viral infections
- Whooping cough
July 12, 2019
Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.
- Bain BJ, et al., eds. Approach to the diagnosis and classification of blood cell disorders. In: Dacie and Lewis Practical Haematology. 12th ed. London, Eng: Elsevier; 2017. https://www.clinicalkey.com. Accessed June 20, 2019.
- Davids MS. Approach to the adult with lymphocytosis or lymphocytopenia. https://www.uptodate.com/contents/search. Accessed June 20, 2019.
- AskMayoExpert. Lymphocytosis. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2019.
- Coates TD. Approach to the child with lymphocytosis or lymphocytopenia. https://www.uptodate.com/contents/search. Accessed June 20, 2019.
- Kaushansky K, et al., eds. Lymphocytosis and lymphocytopenia. In: Williams Hematology. 9th ed. New York, N.Y.: McGraw-Hill Education; 2016. https://accessmedicine.mhmedical.com. Accessed June 20, 2019.