Causes of a high lymph node count include infection, cancer in the blood or lymphatic system or an autoimmune disorder that causes chronic inflammation. A high lymph node count is medically referred to as lymphocytosis, according to Mayo Clinic.
Specific causes of lymphocytosis are acute lymphocytic leukemia, chronic lymphocytic leukemia and the cytomegalovirus infection. Other specific causes include human immunodeficiency virus (HIV), acquired immunodeficiency syndrome (AIDS), mononucleosis, multiple myeloma and tuberculosis, according to Mayo Clinic. Lymphocytes are an integral part of the immune system and it is normal to see a temporary rise in the lymphocyte count after the body fights off an infection.
A high lymphocyte count may not cause any symptoms, explains Mayo Clinic. It is a doctor's job to determine if it is a harmless and temporary condition or the result of something more serious such as cancer or a chronic infection. However, chronic lymphocytic leukemia may cause symptoms such as weakness, fatigue, weight loss and night sweats, according to the American Cancer Society. A fever and pain in the belly are additional symptoms.
In adults, a count of 3,000 or more lymphocytes in a microliter of blood is considered lymphocytosis. In children, the count range varies and may be anywhere from 7,000 to 9,000 lymphocytes per microliter of blood to be diagnosed as lymphocytosis, says Mayo Clinic.