Leukopenia is when your white blood cell count is below normal, which is around 4,000 μL. It doesn’t always cause symptoms, but it can lead to frequent infections and serious complications.

Your blood is composed of various types of blood cells, including:

  • Red blood cells (RBCs): RBCs carry oxygen from your lungs to the body’s organs, tissues, and muscles.
  • White blood cells (WBCs): WBCs help your immune system fight infections and diseases.
  • Platelets: These blood cells are responsible for blood clotting, such as when you cut yourself.

Leukopenia is when you have a very low number of WBCs.

Keep reading to learn more about the typical WBC levels, as well as the symptoms, causes, and treatments for leukopenia.

WBC counts are typically reported as part of a blood test called a complete blood count (CBC). The results can be reported as cells per microliter (μL) of blood or as cells per cubic millimeter (mm³) of blood.

According to Blood Cancer United, the typical ranges of WBCs are:

  • Males: 5,000 to 10,000 μL
  • Females: 4,500 to 11,000 μL
  • Children: 5,000 to 10,000 μL

Generally, when WBC numbers fall below these reference ranges, you have leukopenia. A doctor, such as a primary care doctor or hematologist, will order additional tests to determine what’s causing your low WBC levels.

It’s important to note that WBC reference ranges can vary based on the laboratory performing the test. Therefore, always refer to the reference ranges listed on your test results report.

In most cases, leukopenia itself doesn’t cause any symptoms. But it increases your risk of developing frequent infections, which can cause symptoms. These may include:

Many diseases and conditions can cause leukopenia, such as:

Blood cell or bone marrow conditions

WBCs originate from the stem cells in the bone marrow. As a result, conditions affecting blood cells or the bone marrow can lead to leukopenia. Some examples of such conditions include:

Your spleen is also important in the production of WBCs. Splenomegaly, or an enlarged spleen, may also lead to leukopenia.

Treatments for cancer

Cancer treatments aim to target and eliminate rapidly dividing cancer cells within the body. However, because blood cells also grow rapidly, some cancer treatments can destroy these cells as well.

Some cancer treatments that may lead to leukopenia include:

Congenital disorders

Congenital disorders are present at birth. The ones that can lead to leukopenia include conditions that affect how bone marrow works to make blood cells, such as:

  • Kostmann syndrome (severe congenital neutropenia)
  • myelokathexis

Infectious diseases

Several infectious diseases may also cause leukopenia, including:

Other acute viral infections, such as the flu or any very severe infection, can also lead to leukopenia.

Autoimmune disorders

Some autoimmune disorders can destroy WBCs or bone marrow stem cells, which make blood cells, and can lead to leukopenia. Examples of autoimmune disorders that may cause leukopenia are:

Malnutrition

Leukopenia can be caused by vitamin or mineral deficiencies, such as deficiencies in:

Medications

Certain medications can also cause leukopenia as a side effect. Some examples are:

Sarcoidosis

Sarcoidosis is a systemic illness caused by an exaggerated immune response. It’s characterized by the formation of granulomas, or small areas of inflammation, in multiple systems in your body. When these granulomas form in your bone marrow, leukopenia can result.

There are several different types of leukopenia, depending on which type of WBC is low in your blood. The types of WBCs include:

Each WBC type has a different function in protecting your body from infections or harmful substances.

If your blood is low in neutrophils, you have a type of leukopenia known as neutropenia. Neutrophils are the WBCs that protect you from many types of infections, particularly those involving fungi or bacteria.

Neutrophils make up 55% to 70% of your total WBC count, so leukopenia is often caused by a decrease in neutrophils. In fact, some people use the terms “leukopenia” and “neutropenia” interchangeably.

Another common type of leukopenia is lymphocytopenia. This is characterized by a low number of lymphocytes, which are the WBCs that protect you from a variety of infections and also from cancerous cells.

A CBC is one of the first tests used to help diagnose leukopenia. This test informs a doctor about the levels of WBCs, RBCs, and platelets in your blood.

A CBC can show that your overall levels of WBCs are low. However, a doctor will also likely order a CBC with a differential, which breaks down the levels of different types of WBCs. This can help determine the specific type of WBC that’s low.

If your WBC count is low, a doctor will likely repeat the test to confirm the results, as it’s possible that leukopenia is transient or a laboratory error.

If the second test also reveals low WBC, then your doctor will order other tests to help determine the cause of your condition. Some examples include:

Treatment for leukopenia depends on which type of WBC is low and the underlying cause. You may also need additional treatments to manage any infections that develop due to insufficient WBCs.

Common treatments may include:

  • stopping treatments or medications that cause leukopenia
  • treating underlying conditions that cause leukopenia, such as lupus or sarcoidosis
  • taking certain medications, such as antifungals or antibiotics
  • taking granulocyte-colony stimulating factor (G-CSF), such as filgrastim (Neupogen) and pegfilgrastim (Neulasta)
  • getting a hematopoietic stem cell transplant (HSCT)

How serious is leukopenia?

Leukopenia involves low levels of infection-fighting immune cells, which can cause potentially serious complications if left untreated. These may include:

  • needing to delay cancer treatment because of a mild infection
  • recurrent or prolonged infections
  • sepsis
  • septicemia
  • premature death

You can’t prevent leukopenia, but you can take action to prevent infections when your WBC count is low.

Historically, oncologists and cancer centers have recommended a low-bacterial diet, or neutropenic diet, to help reduce the risk of consuming food contaminated with bacteria.

However, support for the effectiveness of this diet is lacking, and some research suggests that such a diet isn’t associated with a decreased infection risk.

Instead, healthcare professionals currently focus on nutrition education and food safety practices. If your WBC counts are low, consider limiting:

  • raw or undercooked meat, poultry, or seafood
  • raw or undercooked eggs, including foods that contain raw eggs, such as homemade mayonnaise or hollandaise sauce
  • raw or unpasteurized dairy products
  • raw sprouts

It’s also vital to focus on safe food handling and infection prevention. Some tips include:

  • frequently washing your hands, such as:
    • before touching your nose, mouth, or eyes
    • after being out in public
    • after using the toilet
    • after coughing, sneezing, or blowing your nose
    • before and after handling or preparing food
    • before eating
    • after touching or handling animals
    • after handling garbage
  • limiting your risk of cuts, such as by using an electric razor, wearing shoes outside, and brushing your teeth with a soft-bristle toothbrush
  • properly rinsing fresh produce under running tap water
  • separating food types, such as raw meats from other foods
  • cooking foods to minimum safety temperatures
  • cleaning kitchen utensils, cutting boards, and countertops with soap and warm water
  • promptly storing cooked foods in the refrigerator

Leukopenia is when the levels of WBCs in your blood are lower than the reference range, around 4,000 μL.

People with leukopenia have an increased chance of infection. In fact, you may not realize you have leukopenia until you develop symptoms of an infection, such as fever or chills.

A variety of conditions can cause leukopenia, including certain types of cancer, infectious diseases, and autoimmune diseases. If you’re at risk of developing leukopenia, a doctor will routinely check your WBC count to help lower your chance of complications.

Depending on the cause, leukopenia can be treated in several ways. While your WBC count is low, you can also make dietary and lifestyle changes to help reduce your chance of infection.

If you have leukopenia and symptoms of an infection, contact your doctor right away.