Complete Blood Count

Your Care Explained > Tests and Procedures : Complete Blood Count

A complete blood count, often referred to as a CBC, provides detailed information about three major components of your blood: red blood cells, white blood cells and platelets.

Women tend to have lower red blood cell counts and hemoglobin and hematocrit values than men do, particularly before menopause, a condition primarily due to blood loss during menstruation.

White Blood Cell (WBC) Count

White blood cells fight infection. A normal WBC is 4,500 to 10,000 per cubic milliliter (uL). A high WBC can indicate inflammation or infection and the use of certain drugs like aspirin, heparin and corticosteroids. A low WBC can signal bone-marrow abnormalities, liver problems, other diseases, like lupus, or use of certain medications, including antibiotics, antihistamines and diuretics.

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Red Blood Cell (RBC) Count

Red blood cells carry oxygen to the tissues and pick up waste products from them. They are measured in millions per cubic milliliter (mil/uL) of blood. The normal range is 4.2 to 5.4 mil/uL. RBCs below that range may be due to bleeding, certain blood cancers, nutritional deficiencies or fluid retention. Women tend to have lower RBCs than men, primarily due to blood loss through menstruation. RBCs above the normal range may result from dehydration, certain heart and/or lung conditions or polycythemia.

Hemoglobin (HGB) Value

Hemoglobin not only gives red blood cells their color, it is the molecule that picks up inhaled oxygen in the lungs. It also takes carbon dioxide back to the lungs to be exhaled. Hemoglobin is measured in grams per deciliter (g/dL) of blood. The normal range for women is 12.1 to 15.1. A low HGB may be the result of low levels of RBCs and have similar causes, but it may also mean that too little hemoglobin is being produced. A high HGB count is usually due to the same conditions as a high RBC.

Hematocrit (HCT) Value

The hematocrit is the percentage of red blood cells in relation to your total blood volume. The normal range for women is 36.1 to 44.3. Abnormal HCT values usually signal the same disorders as abnormal RBCs and HGB values.


Platelets are disc-like structures that play an important role in blood clotting. The CBC measures the number and size of platelets present in a cubic milliliter of blood. The normal range is 150,000 to 400,000. A low platelet count can signal a risk for excessive bleeding or bruising and may be the result of anemia or coagulation disorders.

Date Last Modified: January 21, 2011

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