Home Health A-Z Lymphocytosis (High Lymphocyte Count)-Causes, Symptoms & Treatment

Lymphocytosis (High Lymphocyte Count)-Causes, Symptoms & Treatment

Verified By Apollo Doctors August 8, 2021 191050 0

Lymphocytosis refers to the increase in the number or proportion of a type of white blood cell called lymphocytes. Lymphocytes are white blood cells present in the body that help fight infections and other viruses entering the human body. A temporary increase in the number of lymphocytes means the body is fighting bacteria or other harmful germs that invade the body. But it can also be an indication of a serious condition.  

In adults, lymphocytes ranging above 5000 per microliter are considered lymphocytosis. But the number varies in children. Counts above 7000 per microliter and 9000 per microliter indicate lymphocytosis in older children and infants, respectively.

How common is Lymphocytosis?

The rise in the number of lymphocytes is expected after a viral infection. It can also happen to people who have an adverse reaction to certain medicines, have rheumatoid arthritis, face a severe illness/trauma, are affected with cancers such as leukemia, lymphoma or have undergone a spleen removal procedure.  

What is the function of Lymphocytes?

Lymphocytes are of three types – T cells, B cells, and NK cells. B lymphocyte cells are helpful for the formation of antibodies in the body. The T cells are used to kill cancer cells and also protect your body from foreign substances. The NK cells are natural killers. These cells are specialized in killing the virus cells as well as the cancer cells. The natural killer cells are specialized in targeting the infected cells. 

What are the causes of lymphocytosis? 

The normal range of lymphocytes varies from 800 to 5000 lymphocytes per ml of blood. It is mainly 18% to 45% of the White Blood Cells (WBC) count. The number of lymphocytes also varies according to the age of a person. Lymphocytosis is very common. It is common particularly in people who have:

  1. Had a recent infection (most commonly viral)
  2. A reaction to a new medication 
  3. A medical condition which causes long-lasting inflammation, such as arthritis
  4. Severe medical illness like trauma
  5. Some types of cancer, such as leukemia or lymphoma
  6. Had their spleen removed

There are multiple reasons for this disease. Specific causes of lymphocytosis include


Lymphocytosis can occur due to cancer also. In some cancers, lymphocytosis acts as an early indicator. Cancers that cause lymphocytosis are: 

  • Chronic lymphocytic leukemia.
  • Large granular lymphocyte leukemia.
  • Acute lymphoblastic leukemia.
  • Non-Hodgkin lymphoma.

Other viral infections

Viral infections are a very common cause of lymphocytosis. Infections occur when bacteria or parasites harmful to the human body enter it. Lymphocytes multiply to fight these bacteria and enables the body free of foreign particles. Some of the common infections that cause lymphocitosis are:  

Other causes

Lymphocytosis can also be caused due to excessive smoking, medical emergency due to stress, autoimmune diseases and allergies to medications. 

What are the symptoms of Lymphocytosis?

There are usually no severe symptoms of lymphocytosis. If lymphocytosis is due to severe disease, there might be some symptoms. These symptoms are swelling in the lymph nodes in the neck region, armpits, and near your stomach. Other symptoms include shortness of breath, severe pain, fever, night sweats, loss of appetite, fatigue, infection, nausea, vomiting, etc.

When to Consult the Doctor?

If you have severe symptoms and the effects of this disease persist, you must consult a doctor. The doctor will guide you and ask you to undergo tests. If your Complete Blood Count report shows a high level of lymphocytes, it can indicate lymphocytosis. If you have a family history of such an illness, you must take extra care.

How is Lymphocytosis diagnosed?

Lymphocytosis is diagnosed by CBC (Complete Blood Count) blood test. CBC helps us determine the number of white blood cells in the blood and the lymphocytes present in the white blood cells. Other procedures include bone marrow biopsy, which helps find the root cause of lymphocytosis. One of the important points that doctors might look into is your medical history and medications and conduct other examinations.

The diagnosis of lymphocytosis shows that you have or have earlier had an infection or illness. In most cases, lymphocytosis simply means that our body has been fighting a viral infection.

In a few cases, lymphocytosis is one of the first signs of certain blood cancers, such as chronic lymphocytic leukemia (CLL) – the most common type of leukemia observed in adults. Further diagnostic tests are usually necessary to rule out other conditions and make a firm diagnosis of the cause of lymphocytosis. 

What tests will be done to diagnose Lymphocytosis?

A complete blood check confirms lymphocytosis by showing the excessive proportion of lymphocytes in the blood. A bone marrow biopsy may also be recommended by the healthcare provider to find out the root cause of the multiplication of lymphocytes. A flow cytometry test may help to find out if the cells are clonal in nature which confirms signs of chronic lymphocytic leukemia. 

Lymphocytosis Treatment 

The treatment of lymphocytosis involves the treatment of the reason. Most cases of lymphocytosis are cured by treating the underlying disease, which can be the primary cause of the disease. 

Cancer can also cause lymphocytosis. In such cases, doctors advise chemotherapy. Generally, more than one drug is used, or a combination of drugs is used that target the affected cells. Chemotherapy is usually done in three- to four-week cycles. The duration may be extended, depending on the severity. The gap between weeks is to allow the cells to heal and repair. There might be some side effects like fever, nausea, low blood counts, etc.

Immunotherapy is another complex procedure to treat severe cases of lymphocytosis. In immunotherapy, the drugs are used to help your immune system identify the cells and destroy these cells.

Other forms of treatment include targeted cell therapy, stem cell therapy, etc. These treatments are generally used to treat severe cases of lymphocytosis.

What are the complications associated with lymphocytosis?

As already mentioned, lymphocytosis can be a first indicator of serious cancers including chronic lymphocytosis. It can also be due to other chronic medical conditions and the chances of it have to be crossed out by confirming with appropriate tests. 


Lymphocytosis cannot be prevented entirely. There are only some ways through which its risk can be reduced.

  • Keeping a safe distance from an infected person and avoiding sharing your personal items with a sick person.
  • Disinfecting items of common use.
  • Cleaning your hands frequently with soap and water


The number of lymphocytes in the blood can vary significantly. The high number of lymphocytes may or may not cause symptoms or signs. It is important to have a regulated number of lymphocytes in the white blood cells. Both higher and lower numbers can be harmful to the body.

Frequently Asked Questions

Does lymphocytosis lead to leukemia? 

Though it is a rare phenomenon, lymphocytosis can lead to leukemia. There is a type of lymphocyte called B-cell among the lymphocytes. These particular monoclonal cells can progress into chronic lymphocytic leukemia in rare cases. 

Is lymphocytosis serious?

Most of the time, lymphocytosis is a less dangerous condition. It can occur as a result of infections or flu. But in rare cases it may indicate cancer or other severe conditions which have to be confirmed with appropriate tests recommended by the healthcare provider.

What does it mean when your lymphocytes are high?

High lymphocyte count in human blood refers to a condition called lymphocytosis which is very common in people after getting affected by an infection. But care has to be taken to confirm there is no underlying reason behind the sudden rise in its count. 

Can lymphocytosis be cured?

 Lymphocytosis is a condition which can be treated by addressing the underlying cause behind the sudden rise in the lymphocyte count. It can be due to infection or can even be due to cancer. 

Can stress cause lymphocytosis? 

Stress and anxiety cause imbalance in a person’s immune system. It can cause a rise in the lymphocyte counts and cause lymphocytosis. 

How long does lymphocytosis last? 

Lymphocytosis will last until the underlying cause behind the rise in lymphocyte count is cured. Treatment of the cause should cure this condition. 

What is the outcome after the treatment of lymphocytosis?

The treatment of the underlying cause behind lymphocytosis can cure the rise in the lymphocyte count and cure the condition. 

When should I be concerned about lymphocytes?

 If you are persistently having infections and chronic symptoms that do not subside, you may consult the healthcare provider to confirm the underlying cause behind lymphocytosis.

Who is most at risk for getting lymphocytosis?

Lymphocytosis is a very common condition among people and anyone can be affected by it. But people with infections, arthritis, excessive stress, and certain types of cancers are more prone to it. 

Verified By Apollo Doctors
At Apollo, we believe that easily accessible, reliable health information can make managing health conditions an empowering experience. AskApollo Online Health Library team consists of medical experts who create curated peer-reviewed medical content that is regularly updated and is easy-to-understand.

Quick Appointment



Book ProHealth Book Appointment
Request A Call Back X