Causes

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
• HIV/AIDS
• Hypothyroidism (underactive thyroid)
• Lymphoma
• Mononucleosis
• Other viral infections
• Syphilis
• Tuberculosis
• Whooping cough