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Complete Blood Count (CBC) (cont.)

Function of Cells in a Complete Blood Count

The cells in a complete blood count serve very important functions in the body.

The white blood cells are an important component of the immune system which fights against infections in the body. They are made in the bone marrow and undergo a complex series of steps to gain functional maturity at which time they are released into the blood stream to perform their function. An elevated WBC count typically indicates some kind of infection or inflammation in the body. Each of the cells in the WBC differential also has specific functions that are important to note when analyzing the results of a complete blood count. For example, eosinophils may be involved in allergic reactions. Neutrophils are usually more suggestive of a bacterial infection whereas lymphocytes typically suggest a viral infection. Physicians will sometimes refer to a left shift on the differential which means that the neutrophils are elevated or they may refer to a right shift which indicates that the lympocytes are elevated.

Red blood cells are a vital part of the oxygen transportation system in the body. The hemoglobin molecule is a complex protein structure that exists within the red blood cells and is the physical carrier of oxygen from the lungs to all other parts of the body. Decreases in the red blood cell count or the hemoglobin level may interfere with the oxygen carrying capacity of the red blood cells. A diagnosis of anemia indicates a low number of RBCs or a low level of Hgb.

Platelets are an important part of the blood clotting system. They are not complete cells, but fragments of larger cells called megakaryocytes. Platelets become activated when there is any evidence of bleeding or injury somewhere in the body. They clump together at the site of bleeding (called platelet aggregation) in an attempt to plug up the bleeding site. This is done in concert with other components of the clotting system which includes some specific proteins such as thrombin.

Medically Reviewed by a Doctor on 8/13/2015

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