Erythrocyte indices; Blood indices; Mean corpuscular hemoglobin (MCH); Mean corpuscular hemoglobin concentration (MCHC); Mean corpuscular volume (MCV); Red blood cell indices
Red blood cell (RBC) indices are part of the complete blood count (CBC) test. They are used to help diagnose the cause of anemia, a condition in which there are too few red blood cells.
The indices include:
See also: RBC count
Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.
Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
The values for MCHC, and MCH are calculated from the hemoglobin (Hgb), hematocrit (Hct), and RBC count:
The MCV is measured directly by a machine.
No special preparation is necessary.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
RBCs transport hemoglobin which, in turn, transports oxygen. The amount of oxygen tissues receive depends on the amount and function of RBCs and hemoglobin.
The MCV reflects the size of red blood cells. The MCH and MCHC reflect the hemoglobin content of red blood cells. These RBC measures are used to diagnose types of anemia.
Anemias are defined based on cell size (MCV) and amount of Hgb (MCH).
Zuckerman K. Approach to the anemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 162.
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