Causes of an increase in the proportion of white blood cells include pregnancy, stress, exercise, allergies and tissue damage, according to Healthline. Additionally, medical conditions such as anemia, leukemia, asthma, bone marrow tumors, and inflammatory conditions such as bowel disease may also trigger a high white blood cell count. Normal white blood cell counts range between 4,500 and 10,000 white blood cells per microliter, and figures above this range indicates a high white blood cell count, or leukocytosis.
As part of the body's immune system, white blood cells prevent infection by attacking germs, virus and bacteria, explains Healthline. A white blood cell count is a test that measures the quantity of white blood cells in the body. Doctors order the test to diagnose illnesses, detect infections, and monitor the effectiveness of treatments. The test is also part of the annual physical examination for all patients.
The white blood cell count requires no special preparation, expounds Healthline. However, there are certain medications that interfere with test results by raising or lowering the correct count. These medications include corticosteroids, antibiotics, barbiturates, antihistamines and chemotherapy drugs. Thus, patients needs to inform their doctor of all medications they're taking at the time of the test.