Low White Blood Cell Count

A low white blood cell count is an unusually low number of one or more kinds of white blood cells.

• A low white blood cell count puts you at increased risk of infection, which can be life-threatening

• A low white blood cell count can be a side effect of drugs, particularly chemotherapy drugs

• Sometimes a low white blood cell count is caused by an infection or cancer

• Doctors may do blood tests and bone marrow tests to see why your white blood cell count is low

• Doctors may give you medicine to increase your white blood cells and antibiotics if you have a fever or other signs of infection

There are many causes of a low white blood cell count:

• Drugs: Many drugs, but particularly chemotherapy drugs

• Infections: HIV, many other viral infections, and severe bodywide bacterial infection (sepsis)

• Cancer that starts in the bone marrow, such as leukemia, lymphoma, and myeloma

• Metastatic cancer in the bone marrow, such as from breast cancer or prostate cancer

• Other bone marrow problems, such as myelodysplastic disorders

• Radiation therapy that involves the bone marrow

A low white blood cell count has no specific symptoms. You get symptoms because you develop frequent infections. Sometimes the infections are unusual ones that most people don't get.

Symptoms of infections can start suddenly or slowly and can include:

• Fever

• Rash

• Swollen lymph nodes

• Painful sores in your mouth and anus (the opening at the end of the digestive tract where stool comes out)

Doctors can tell you have a low white blood cell count by doing a routine complete blood count (CBC). If you're getting treatments or have a disease that can lower your white blood cell count, doctors check your CBC often.

Sometimes, the cause is obvious, such as if you’re getting chemotherapy or radiation therapy for cancer.

If the cause isn't clear, doctors may do:

• Blood, urine, and imaging tests looking for infection

• Bone marrow biopsy (removing some bone marrow with a needle to do tests on it)

Doctors treat a low white blood cell count using:

• Antibiotics to treat any infections

• Medicines that cause your body to make more white blood cells

• Treatment for any diseases that may be causing the count to be low