High White Blood Cell Count


What is a high white blood cell count?

A high white blood cell count is also called leukocytosis. This means the numbers of white blood cells are higher than the normal range.

What is a white blood cell?

White blood cells are the part of the blood that fight infections. All blood cells, including white blood cells, are made in the bone marrow.

What is a complete blood count?

A complete blood count (CBC) is a blood test that is commonly ordered by doctors. A CBC is often ordered as part of a complete physical or when your doctor thinks you might have a certain condition, such as an infection. A CBC may also be done to check on levels of prescribed medications in the body.The test (which actually consists of several tests) gives details about three types of blood cells: red blood cells, white blood cells and platelets. The CBC reports how many cells there are in the blood, and the physical characteristics of the cells, such as size, shape and content.

Why would your doctor order a white blood cell count test?

White blood cell tests are usually part of the CBC. However, your doctor might order a white blood cell count if you have:

  • Fever
  • Body aches
  • Headaches
  • Chills
  • Night sweats
  • Swollen lymph nodes or enlarged spleen

Test Details

What does a white blood cell count test tell?

White blood cells are measured in the number per microliter, and a “normal” count is generally a range. Different laboratories might use different ranges. In general, the normal range for men is 5,000-10,000 white blood cells per microliter of blood. For women who are not pregnant, the range is 4,500-11,000 white blood cells per microliter. For children, the range is 5,000-10,000.

A type of test called a white blood cell differential (sometimes called a “diff”) might be done at the same time as the other blood tests. This test classifies the different kinds of white blood cells, which all have different jobs in keeping us healthy.

There are five main types of white blood cells:

  • Neutrophils (also called segs, PMNs, granulocytes, or grans)
  • Lymphocytes
  • Monocytes
  • Eosinophils
  • Basophils

Results and Follow-Up

What does a high white blood cell count mean?

The following conditions can cause white blood cell counts to be high:

  • Viral or bacterial infection
  • Inflammation
  • Excessive physical or emotional stress (such as fever, injury, or surgery)
  • Burns
  • Immune system disorders such as lupus or rheumatoid arthritis
  • Thyroid problems
  • Certain medicines, including lithium, corticosteroids, and beta agonists (used to improve breathing)
  • Removal of the spleen
  • Smoking
  • Obesity

More serious conditions that may cause high white blood cell counts include blood disorders, including:

Last reviewed by a Cleveland Clinic medical professional on 01/11/2018.


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  • Leukemia & Lymphoma Society. Understanding blood counts. (https://www.lls.org/managing-your-cancer/lab-and-imaging-tests/understanding-blood-counts) Accessed 2/15/2018.
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