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What Are the Causes of WBC?

White blood cells (WBC), also called leukocytes, are part of the body's defense against foreign substances and infections. Doctors measure the count of white blood cells as part of a routine blood test, and the WBC count is an important way for the doctor to gauge how healthy you are. Urine tests also screen for the presence of white blood cells. An abnormal number of white blood cells can indicate disease or infection. There are many subtypes of white blood cells. According to MayoClinic.com, abnormalities in your WBC count usually only affect one type of WBC.

  1. Causes of High WBC

    • Increased white blood cells may indicate the body's efforts to fight off an infection. Inflammatory diseases may cause high WBC count. Examples of these diseases include allergies, particularly severe allergic reactions and diseases such as rheumatoid arthritis. Other causes of high WBC count include anemia, tissue damage, leukemia and severe emotional or physical stress. Certain medications may cause high WBC count, such as corticosteroids, heparin, aspirin and chloroform. Smoking can also cause an increase in WBC count. High WBC count is called leukocytosis. This condition usually has 10,500 leukocytes in a microliter of blood.

    Causes of Low WBC

    • Low WBC count indicates a decrease in disease-fighting cells circulating in your blood. Certain medications or conditions can weaken the immune system and cause a decrease in WBC. Specific causes of low WBC include disease of the spleen or liver or exposure to radiation. Conditions that disrupt bone marrow function also may trigger low WBC count. Examples include viral infections, cancer and autoimmune disorders. Medications that may cause low WBC include diuretics, barbiturates, anti-thyroid drugs, antibiotics and chemotherapy drugs. Low WBC count is known as leukopenia. A low WBC count is usually defined as fewer than 3,500 cells per microliter of blood according to MayoClinic.com.

    WBC in Urine

    • Routine urine tests check for the presence of abnormalities in the urine, including white blood cells. Healthy urine does not contain white blood cells and the presence of these cells in the urine is an indicator of disease or infection. A urinalysis screens for leukocyte esterase, an enzyme present in most white blood cells. The cause of WBC in the urine is usually related to problems with the kidneys or urinary tract. White blood cells in the urine are known as leukocyturia. According to Lab Tests Online, the most common cause of leukocyturia is a bacterial urinary tract infection such as a kidney infection or bladder infection.

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