What Is Lymphopenia?

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Lymphopenia (also known as lymphocytopenia) is a blood disorder that involves a reduced level of lymphocytes, which are white blood cells that help protect you from infection. Lymphocytes are an important part of the immune system and lymphopenia increases your risk of infections.

Lymphopenia can have many causes, such as viral or bacterial Infections, medications, inherited conditions, or autoimmune disorders. When treatment is needed, it will depend on the underlying cause.

This article explains lymphopenia, its causes, and how it's diagnosed and treated.

Close up of scientists hands selecting a blood sample for medical testing
Andrew Brookes / Getty Images

What Are Lymphocytes?

The vast majority of cells in our blood are erythrocytes (red blood cells) which are responsible for transporting oxygen throughout the body. This is followed by thrombocytes (platelets) and leukocytes (white blood cells).

Leukocytes are produced in the bone marrow and circulate freely in the bloodstream as part of the immune system. Lymphocytes represent the largest proportion of these cells, ranging anywhere from 20% and 40%.

Lymphocytes can be further broken down into three subsets:

  • Natural killer (NK) cells serve as the first line of defense for the immune system.
  • T cells are produced in response to a specific pathogen.
  • B cells produce antibodies that help other cells identify and neutralize pathogens.

Lymphopenia may be identified by the type of lymphocyte affected. For example, human immunodeficiency virus (HIV) specifically targets CD4 T cells for infection, resulting in massive losses of that specific cell. The loss of B cells is more associated with immune-suppressive drugs (such as those used for organ recipients) while NK depletion is typically a rare situation.

What Causes Lymphopenia?

Lymphopenia can be caused by many conditions, including infection, poor nutrition, and medication side effects. At times, the condition may only affect lymphocytes. In others, it can be the result of a depletion of all white blood cells.


Viruses, bacteria, fungi, or parasites are all pathogens that can cause infections that may lead to lymphopenia. When lymphopenia is related to an infection, it is considered pathogenic.

Infections may kill off white blood cells faster than they can be produced or temporarily disrupt bone marrow.

Infections that can cause lymphopenia include:

Medical Treatments

Certain medications and medical treatments can destroy white blood cells and cause lymphopenia. This includes:

When the treatment for viral hepatitis includes the medications peginterferon and ribavirin, it can cause suppression of lymphocytes in some people. In others, it can affect the entire range of white blood cells (leukopenia).

Nutritional Deficiencies

Not eating enough protein, vitamins, or minerals can cause lymphopenia. Poor nutrition is a major risk factor for lymphopenia worldwide.

Excessive Alcohol

Drinking too much alcohol, especially chronic heavy drinking, affects the immune system and can lead to lymphopenia.

Inherited Conditions

Inherited conditions that involve diminished bone marrow function can cause lymphopenia.

Inherited conditions include:

Blood Cancer or Blood Diseases

Blood cancers or other blood diseases that damage marrow or disrupt the production of blood cells can lead to lymphopenia. Cancers and blood diseases include:

  • Hodgkin lymphoma, a blood cancer that develops in lymphocytes
  • Leukemia, a cancer of blood-forming tissues
  • Aplastic anemia, a condition in which the bone marrow stops producing enough red blood cells, white blood cells, and platelets.
  • Myelodysplastic syndromes, a group of disorders which disrupt the production of blood cells

Autoimmune Disorders

Autoimmune disorders that destroy white blood cells or bone marrow cells can cause lymphopenia.

This includes:

Lymphopenia Symptoms

Lymphopenia may not have any symptoms yet it may get discovered during routine blood tests.

When there are signs and symptoms of lymphopenia, they may include:

  • Frequent infections, such as colds or pneumonia
  • Unusual (fungus, parasites) or long-lasting infections (TB)
  • Missing or abnormal tonsils 
  • Swollen lymph nodes
  • Skin conditions or abnormalities
  • Failure to grow and gain weight


Your healthcare provider can diagnose lymphopenia based on a combination of your personal and family medical history, a physical exam, and test results. 

During a physical exam, swollen lymph nodes, skin issues, or a spleen that is larger than normal may be noticed.

Tests may include:

  • A complete blood count: Checks the numbers of lymphocytes and other white blood cells, as well as red blood cells, platelets
  • Flow cytometry: Measures the levels of the different types of lymphocytes
  • Immunoglobulin level tests: Checks the levels of antibodies called immunoglobulins, made by B lymphocytes

An overall low white blood cell count (leukopenia) is most often detected when your healthcare provider orders a test for a condition you're already experiencing. A low count is rarely an unexpected finding.

In some cases, the type of white blood cell affected may be enough to point you in the direction of a diagnosis. At other times, you may need additional tests to piece together a cause.

Other tests can check for different diseases that cause lymphopenia such as HIV, COVID-19 or other viruses, tuberculosis, or other blood or immune conditions. Your provider may also test your bone marrow or your lymph nodes.

What Is a Low Level of Lymphocytes?

Adults may be diagnosed with lymphopenia if they have less than 1,500 lymphocytes per microliter of blood. For children, it varies based on their age. Children ages 6 and younger may be diagnosed with lymphopenia if they have less than 2,000 lymphocytes per microliter of blood.

How Do You Treat Lymphopenia?

Mild cases of lymphopenia may resolve on their own without treatment.

When treatment is needed, it will be based on the underlying cause and the specific health condition that is causing the lymphopenia. This may include treatments for particular infections, cancers, or autoimmune disorders, for example.

If your white blood cell count is very low, you may need to take special precautions to prevent illness. This includes avoiding others who may be ill, wearing a face mask if you are in a confined space (such as an airplane) with others, and washing your hands regularly and thoroughly.


Lymphopenia is when your blood doesn't have enough lymphocytes, a type of white blood cells. It puts you at risk of new infections and getting sick.

Lymphopenia can be caused by infections, such flu or COVID-19, or may be due to conditions that affect the blood and bone marrow. Poor diet or heavy drinking can also lead to it.

If treatment is needed, it will target the underlying cause.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Charles Daniel
 Charles Daniel, MPH, CHES is an infectious disease epidemiologist, specializing in hepatitis.