Definition:
The erythropoietin test measures the amount of a hormone called erythropoietin ((EPO) in blood. The hormone acts on stem cells in the bone marrow to increase the production of red blood cells. It is made by cells in the kidney, which release the hormone when oxygen levels are low. See also: Reticulocyte count
Alternative Names:
Serum erythropoietin; EPO
How the test is performed:
Blood is 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.
How to prepare for the test:
No special preparation is necessary.
How the test will feel:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed:
This test may be used to help determine the cause of anemia, polycythemia (high red blood cells) or other bone marrow disorders. A change in red blood cells will affect the release of EPO. For example, persons with anemia have too few red blood cells, so more EPO is produced.
References:
Mathur S, Schexneider K, Hutchison RE. Hematopoiesis. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 30.
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