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Alternative NamesErythrocyte indices; Blood indices; Red cell mass measurement; Mean corpuscular hemoglobin (MCH); Mean corpuscular hemoglobin concentration (MCHC); Mean corpuscular volume (MCV); Red blood cell indices
Definition Return to top
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
How the Test is Performed Return to top
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 red blood cell count (RBC):
The MCV is measured directly by a machine.
How to Prepare for the Test Return to top
No special preparation is necessary.
How the Test Will Feel Return to top
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.
Why the Test is Performed Return to top
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).
Normal Results Return to top
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean Return to top
This test is used to diagnose the cause of anemia. The following are the types of anemia and their causes:
Risks Return to top
There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
References Return to top
Zuckerman K. Approach to the anemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 162.Update Date: 2/13/2009 Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.