What Causes an Elevated White Blood Cell Count?

An elevated white blood cell count occurs when the white blood cells, also referred to as leukocytes, increase in response to infection or illness, according to MedlinePlus. Specific causes of high white blood cell counts include bacterial infections, leukemia, excess stress, allergies and anemia.

Elevated white blood cell counts can also be caused by certain medications such as corticosteroids, as well as disorders of the immune system, explains Mayo Clinic. The condition is also common in individuals with diseases of the bone marrow that cause excessive production of leukocytes.

Pregnant women and individuals with inflammatory illnesses such as arthritis and inflammatory bowel disease may also produce high levels of white blood cells, explains Healthline. The medical term for elevated white blood cells is leukocytosis. Once a diagnosis is made and a treatment plan is put in place for individuals with leukocytosis, the blood is periodically tested to monitor the state of the condition and determine whether or not treatment has been effective.

In certain cases, patients with elevated white blood cell readings may be required to submit to additional tests in order for an accurate diagnosis to be made, explains Lab Tests Online. Differential blood cell tests help physicians determine the specific types of white blood cells contributing to the illness. Bone marrow biopsies help to determine if the blood contains abnormal cells.