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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Uses of the complete blood count are extensive. In general, the complete blood count can be done as part of routine health exam and general screening by a doctor. It may be ordered if an infection or anemia is suspected. It may also be ordered to evaluate if abnormal bleeding is present.

As mentioned earlier, an elevation of the white blood cell count or an abnormality of the white blood cell differential may be suggestive of an infection or inflammation. A high or a low white blood cell count could also be a sign of underlying cancer such as leukemia or lymphoma.

A low red blood cell or hemoglobin count typically indicates anemia (low blood). Anemia, typically seen as low hemoglobin or low hematocrit on the complete blood count, is a sign of an underlying disease and it is not a disease itself. Anemia can have many causes including blood loss, bone marrow problems, nutritional deficiencies, genetic hemoglobin structural or functional problems (sickle cell or thalassemia), or kidney failure. These are only the most common causes of anemia, and the list of all causes of anemia is very extensive. Anemia found in a complete blood count may be suggestive of ongoing slow blood loss and, therefore, can be used to detect cancers, such as colon cancer. If anemia is detected, usually the MCV and RDW give some additional clues as to the possible causes of anemia.

A low platelet count (thrombocytopenia) may also be detected in the complete blood count. This may be due to bone marrow problems, some medications or excessive alcohol use, immunologic or genetic problems, advanced liver disease, or cancers such as leukemia. The MPV may indicate how rapidly platelets are made in the bone marrow and released into the blood stream. A high platelet count may also be suggestive of an inflammation or blood malignancy, such as leukemia and lymphoma.

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