White blood cells are essential to healthy immune system functioning, as they help fight off infections and other abnormalities in the blood, bone marrow, and lymphatic system. There are several different types of white blood cells, each of which are essential for defending the body against a certain malady, such as a bacteria, virus, fungus, parasite, or allergic reaction. If an individual has a low white blood cell count, his or her body becomes susceptible to serious illnesses and infections. A low white blood cell count can indicate the presence of one or more serious health problems, such as leukemia, hyperthyroidism, aplastic anemia, or an infectious disease. An insufficient number of cells may also be a potentially dangerous side effect from taking certain medications, or receiving chemotherapy and radiation treatments.
It is common for a person with cancer to suffer from a low white blood cell count. A specific type of cancer known as leukemia is particularly devastating to blood cells and the immune system at large. Leukemia directly afflicts the tissue that makes up bone marrow, which in turn leads to fewer healthy white blood cells and an abundance of mutated, damaging ones. Doctors can test for leukemia and other cancers by ordering blood tests and extracting bone marrow to determine the number and condition of white blood cells. Leukemia is usually treated with chemotherapy, radiation therapy, or bone marrow transplants.
Unfortunately, the most popular treatments for leukemia and other types of cancer can also result in a low white blood cell count. Chemotherapy and radiation therapy are intended to seek out and destroy abnormal cells, but innocent, healthy white blood cells can also be damaged during treatment. Many other medications, including some antipsychotic and antidepressant drugs, can deplete white blood cells with long-term use. Physicians commonly prescribe immune boosting drugs to patients to combat the negative effects of cancer treatments and other medications.
A low white blood cell count may also indicate the presence of a serious bacterial, viral, or fungal infection that attacks the immune system, such as the human immunodeficiency virus (HIV). Some congenital disorders, including lupus and myelofibrosis, cause the body to attack its own defense system, depleting bone marrow and white blood cells. Individuals may suffer from aplastic anemia, a condition where the body is unable to produce new blood cells. Vitamin or mineral deficiencies, influenza, typhoid fever, and malaria can also result in a low white blood cell count.