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.

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 high white blood cell count?

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

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

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