What Are the Causes of Leukopenia?

Leukopenia is the medical term to describe the condition in which the body’s white blood cell count is too low. White blood cells are the disease fighters of the blood, working to either produce antibodies to fight an invading virus, or gather around the disease cell to destroy and devour it. When the white blood cell count reaches too low a level, the ability to fight off germs is significantly decreased. There are numerous potential causes of leukopenia, including too many infections in a short period of time, certain medications that destroy or damage white blood cells or the bone marrow, cancer, and immunodeficiency diseases.

There are several different types of white blood cells, collectively known as leukocytes, including neutrophils, basophils, eosinophils, monocytes, and lymphocytes. Each type has a different role in the body, and a different life span. Some may live only for a few days, while others can live for months. In normal circumstances, the body’s bone marrow constantly produces and replenishes lost white blood cells. When certain illnesses interfere with that ability, the white blood cell count drops and leukopenia occurs.

Neutrophils are the most abundant type of white blood cells, and a drastic reduction in these cells is one of the most common causes of leukopenia. Neutrophils have relatively short life spans compared to other types of white blood cells, only living a few hours to a few days. Although they live such a short time, the bone marrow typically produces 80 million per minute.

Infection is one of the most common causes of leukopenia. Specifically, leukopenia is triggered when an infection spreads throughout the entire body, or a string of infections over a short period of time. In both cases, the neutrophils are being used up faster than the bone marrow can replace them.

Chemotherapy treatment and other exposure to radiation are also potential causes of leukopenia. Chemotherapy works by attacking growing cells. While the goal of chemotherapy is to reduce the number of cancer cells in the body, it is not a selective medication; it destroys all growing cells, including white blood cells. Radiation therapy works in a similar manner, also destroying cells indiscriminately.

Immunodeficiency diseases are other potential causes of leukopenia. While acquired immunodeficiency disease (AIDS) is one of the most well-known of this type of disease, the disorder can also be caused by numerous other conditions, such as cancer, congenital diseases, and malnutrition. These disorders may affect any part of the immune system, and hinder the body’s ability to produce or make proper use of the different types of leukocytes.

Determining the underlying causes of leukopenia typically involves one or more lab tests. The condition may be discovered during routine blood work, or when a complete blood count (CBC) test is ordered based on symptoms present. Once the underlying cause is determined, physicians can begin treatment when available.