Lymphocytosis is a medical condition characterized by elevated amounts of lymphocytes, a type of white blood cell, in the body. There are three main types of lymphocytes: natural killer cells, T cells, and B cells. Each is important when it comes to defending the body from illness and disease. Lymphocytosis itself is not an illness, but is rather a condition caused by an illness or other problem.
In order to be diagnosed with lymphocytosis, an adult must have a lymphocyte count over 4,000 per microliter. Typically, this condition does not have any symptoms, which means the only way to diagnosis it is to perform a blood test.
A variety of infections and diseases can cause elevated lymphocytes. Viral infections are the most common cause, with glandular fever being one of the main ones. Infectious mononucleosis, also known simply as mono or glandular fever, generally affects adolescents and young adults and is spread through blood and saliva. Common symptoms include sore throat, fever, and fatigue.
Bacterial infections such as tuberculosis can also cause lymphocytosis. Tuberculosis is one of the most deadly modern day infectious diseases. It usually effects the lungs, though it may also effect the circulatory system, central nervous system, genitourinary system, lymphatic system, genitourinary system, and the bones and joints.
Symptoms of Lymphocytosis
Lymphocytosis is a feature of infection that is particularly found in children. In the elderly, lymphoproliferative disorders that includelymphomas and lymphocytosis leukemia often present with lymphocytosis and lymphadenopathy. Fever, sore throat, general malaise, atypical lymphocytes in the blood andlymphadenopathy are also the common symptoms of lymphocytosis.
Causes of Lymphocytosis
You may have a lymphocyte count that is higher than would normally be expected but have few, if any, symptoms. Your doctor must then decide if this is a harmless, temporary situation, as can occur after an illness, or if it represents something more serious, such as a blood cancer or a chronic infection. Before deciding if a lymphocyte count is “too high” or is a cause of concern, your doctor may need to perform 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:
- Acute lymphocytic leukemia
- Chronic lymphocytic leukemia
- Cytomegalovirus (CMV) infection
- Multiple myeloma
- Other viral infections
- Whooping cough
Read more about the Treatment of Lymphocytosis