The erythropoietin test measures the amount of a hormone called erythropoietin (EPO) in blood.
The hormone tells stem cells in the bone marrow to make more red blood cells. EPO is made by cells in the kidney. These cells release more EPO when blood oxygen levels are low.
See also: Reticulocyte count
Serum erythropoietin; EPO
How the Test is Performed
A blood sample is needed. For information on how this is done, see: Venipuncture
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 cell count) 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.
The normal range is 0-19 milliunits per milliliter (mU/mL).
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
Increased EPO levels may be due to secondary polycythemia, an overproduction of red blood cells that occurs in response to an event such as low blood oxygen levels. This may happen at high altitudes or, rarely, because of a tumor that releases EPO.
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.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Kremyanskaya M, Najfeld V, Mascarenhas J, Hoffman R. The polycythemias. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, Anastasi J, et al, eds. Hoffman Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Saunders Elsevier; 2013:chap 67.
Kaushansky K. Hematopoiesis and hematopoietic growth factors. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 159.
Reviewed By: Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.