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February 9, 2012

Erythropoietin
(EPO) & The EPO Test

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What is erythropoietin?

Erythropoietin (EPO) is a hormone produced by the kidney that promotes the formation of red blood cells by the bone marrow.

The kidney cells that make erythropoietin are specialized so that they are sensitive to low oxygen levels in the blood that travels through the kidney. These cells make and release erythropoietin when the oxygen level is too low. The low oxygen level may indicate anemia, a diminished number of red blood cells, or hemoglobin molecules that carry oxygen through the body.

Chemically, what is erythropoietin (EPO)?

Erythropoietin is a protein with an attached sugar (a glycoprotein). It is one of a number of similar glycoproteins that serve as stimulants for the growth of specific types of blood cells in the bone marrow.

What exactly does erythropoietin (EPO) do?

Erythropoietin stimulates the bone marrow to produce more red blood cells. The resultant rise in red cells increases the oxygen-carrying capacity of the blood.

As the prime regulator of red cell production, erythropoietin's major functions are to:

  1. Promote the development of red blood cells.

  2. Initiate the synthesis of hemoglobin, the molecule within red blood cells that transports oxygen.

Is the kidney the sole source of erythropoietin?

No. Erythropoietin is produced to a lesser extent by the liver. Only about 10% of the erythropoietin is produced in the liver. The erythropoietin gene has been found on human chromosome 7 (in band 7q21). Different DNA sequences flanking the erythropoietin gene act to control liver versus kidney production of erythropoietin.




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Erythropoietin (EPO Test)

What are the kidneys?

The kidneys play key roles in body function, not only by filtering the blood and getting rid of waste products, but also by balancing levels of electrolyte levels in the body, controlling blood pressure, and stimulating the production of red blood cells.

The kidneys are located in the abdomen toward the back, normally one on each side of the spine. They get their blood supply through the renal arteries directly from the aorta and send blood back to the heart via the renal veins to the vena cava. (The term "renal" is derived from the Latin name for kidney.)

The kidneys have the ability to monitor the amount of body fluid, the concentrations of electrolytes like sodium and potassium, and the acid-base balance of the body. They filter waste products of body metabolism, like urea from protein metabolism and uric acid from DNA breakdown. Two waste products in the blood can be measured: blood urea nitrogen (BUN) ...

Read the Kidney Failure article »






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