Infections and inflammation usually cause high white blood cell counts, according to the American Association for Clinical Chemistry. The elevated count can be also be attributed to allergic responses, severe stress and pregnancy. Medications such as corticosteroids and epinephrine boost white blood cells as well, according to the Mayo Clinic.
Typically, white blood cell count tests are ordered along with complete blood cell count tests, according to the American Association for Clinical Chemistry. A physician may request these tests when a patient has a fever, body aches and chills. In addition, physicians use these counts to help diagnose disorders of the blood or immune system.
White blood cells, also called leukocytes, are the body's second line of defense against foreign invaders, according to Merck. The body’s physical barriers, such as skin and the lining of respiratory membranes, are the first line of defense. If foreign bodies, such as bacteria and pollen, make their way into the bloodstream, white blood cells discover the foreign bodies and destroy them. This is why an infection or allergic reaction results in elevations in white blood cell counts. Severe mental and physical stress can also spur the body to increase circulating white blood cells, according to MedlinePlus. Leukemia, cigarette smoking and tissue damage increase leukocyte count as well.
Individuals with a history of spleen removal normally have a higher white blood cell count, according to MedlinePlus. The number of white blood cells normally ranges from 4,500 to 10,000 white blood cells per microliter of blood. White blood cells are responsible for helping the body fight infections. There are five types of white blood cells, including basophils, eosinophils, neutrophils, lymphocytes and monocytes.