MedlinePlus Medical Encyclopedia: Erythropoietin

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Erythropoietin

Contents of this page:
Alternative names Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are Special considerations

Alternative names

Serum erythropoietin; EPO

Definition Return to top

This is a test to measure the amount of erythropoietin in blood. See also reticulocyte count.

How the test is performed Return to top

Blood is drawn from a vein, usually on inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to cause the veins below the band to swell with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test Return to top

No special preparation is necessary.

For infants and children:
The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

infant test or procedure preparation (birth to 1 year)
toddler test or procedure preparation (1 to 3 years)
preschooler test or procedure preparation (3 to 6 years)
schoolage test or procedure preparation (6 to 12 years)
adolescent test or procedure preparation (12 to 18 years)

How the test will feel Return to top

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 Return to top

This test may be used to help determine the cause of anemia, polycythemia (high red blood cells) or other bone marrow disorders.

EPO (erythropoietin) is a protein hormone produced by specialized cells in the kidneys. These cells are sensitive to the oxygen concentration in the blood, and increase the release of EPO when the oxygen concentration is low. Since oxygen is carried by red blood cells, too few red blood cells (anemia) will result in erythropoietin release. EPO acts on stem cells in the bone marrow to increase the production of red blood cells.

Normal Values Return to top

The normal range is 0-19 mU/ml (milliunits per milliliter).

What abnormal results mean Return to top

Elevated levels may indicate secondary polycythemia (an increased production of red blood cells in response to a circumstance like low levels of oxygen in the blood).

Lower-than-normal levels may be seen in chronic renal failure or polycythemia vera (when the body makes too many red blood cells for an unknown reason).

What the risks are Return to top

excessive bleeding
fainting or feeling light-headed
hematoma (blood accumulating under the skin)
infection (a slight risk any time the skin is broken)
multiple punctures to locate veins

Special considerations Return to top

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Update Date: 1/16/2004

Updated by: Jacqueline A. Hart, M.D., Department of Internal Medicine, Newton-Wellesley Hospital, Newton, Ma., and Senior Medical Editor, A.D.A.M., Inc. Previously reviewed by Marcia S. Brose, M.D., Ph.D., Division of Hematology/Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA. Review provided by VeriMed Healthcare Network (6/1/2003).

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