Complete Blood Count (cont.)

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What is the complete blood count (CBC) used for?

Your doctor may order this test for a variety of reasons. It may be a part of a routine check-up or screening, or as a follow-up test to monitor certain treatments. It can also be done as a part of an evaluation based on a patient's symptoms.

For example, a high WBC count (leukocytosis) may signify an infection somewhere in the body or, less commonly, it may signify an underlying malignancy. A low WBC count (leukopenia) may point toward a bone marrow problem or related to some medications, such as chemotherapy. A doctor may order the test to follow the WBC count in order to monitor the response to a treatment for an infection. The components in the differential of the WBC count also have specific functions and if altered, they may provide clues for particular conditions.

A low red blood cell count or low hemoglobin may suggest anemia, which can have many causes. Possible causes of high red blood cell count or hemoglobin (erythrocytosis) may include bone marrow disease or low blood oxygen levels (hypoxia).

A low platelet count (thrombocytopenia) may be the cause of prolonged bleeding or other medical conditions. Conversely, a high platelet count (thrombocytosis) may point toward a bone marrow problem or severe inflammation.

Medically reviewed by Rambod Rouhbakhsh, MD, MBA, FAAFP; American Board of Family Medicine


National Institutes of Health

Medically Reviewed by a Doctor on 1/24/2014

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Complete Blood Count - Diagnosis Question: What was your complete blood count (CBC) test used for?