Erythropoietin and the Athlete

by: Josh Hodnik

Many cyclists and endurance athletes have been recently accused of taking EPO (erythropoietin), and this accusation along with the media attention followed it, has put a microscope on the drug. Most Americans have heard of EPO, but very few actually know what it does or why it is used.

Erythropoietin is a glycoprotein hormone that controls red blood cell production. This hormone is produced by interstitial fibroblasts in the kidney, and it is also produced in perisinusoidal cells in the liver. While liver production is more prominent during the fetal and perinatal period, kidney production is more prominent during adulthood. So as adults, we rely on the kidney to produce the erythropoietin that we all need.

Red Blood Cells

I have stated briefly how erythropoietin controls red blood cell production, but perhaps I ought to explain the importance of red blood cells within the human body. Red blood cells, or erythrocytes, are the most common type of blood cell. These cells are developed in bone marrow and circulate through the human body for about 100 days before their components are recycled. The red blood cells cytoplasm is saturated with hemoglobin, which is responsible for the blood’s red color. When there are not enough red cells present, or the red blood cells are undersized, there can be some not-so-pleasant side effects: weakness, shortness of breath, heart palpitations, and decreased energy just to name a few. So obviously red blood cells are a very important component within the human body.


Within all blood cells there exists an iron rich molecule called hemoglobin. This molecule has the responsibility of transporting life supporting oxygen to the entire body. It also carries carbon dioxide back to the respiratory organs to be disposed of. Hemoglobin has an oxygen binding capacity of 1.34mL O2 per gram of hemoglobin, and this increases the total blood oxygen capacity by seventy fold compared to dissolved oxygen in the blood.


Epoeitin is human erythropoietin produced in cell culture using recombinant DNA technology. This synthetic form of erythropoietin is marketed under the names Procrit and Epogen, and is used to treat anemia. At one time this drug was the single most expensive drug paid for by US Medicare, with costs reaching $8,447 per patient, per year.

Benefits of Elevated Red Blood Cells

Now that we know about erythropoietin and it’s relation to red blood cells, hemoglobin, and oxygenation, let’s take a look at how all of this could benefit an athlete. Since red blood cells carry oxygen, having an elevated red blood cell count can dramatically improve an athlete’s capacity and delay fatigue. Anabolic steroids are thought to exert many of their beneficial effects through this exact mechanism of action, although reports that this steroid or that steroid (typically Boldenone or Oxymetholone) possess superior RBC elevating properties, are unfounded.

Blood Doping

The term blood doping refers to the process of increasing red blood cell count in the body to increase athletic performance. Before synthetic EPO was available, an athlete would donate a unit of blood into storage, and then after the body has completely replaced the blood loss (which usually takes about 3 weeks), it is then transfused back into the body. This would create an abundance of red blood cells available in the body, and an increase of oxygen capacity. That method has been outlawed for quite a while.

The availability of a synthetic form of EPO has changed all of this, and has made the process of donating blood to be transfused as inferior. With injections usually taken 3 times per week at a dose of 5,000 IUs per injection, an athlete will often see an increase in hematocrit (the proportion by volume of red blood cells within the blood) by about 10%. This jump in hematocrit may seem minor to most people, but an athlete will experience a large increase in endurance and it will slow lactic acid build up.

The benefits of EPO have attracted the attention of the athletic community and this has led to use by both top and lower level athletes. Some bodybuilders have used EPO to increase vascularity and pumps. Increased exercise endurance while in the weight room would usually accompany the increase in muscle fullness. There was even (briefly) an EPOrp (releasing peptide) on the underground market a few years back.

There have been some problems while using synthetic EPO. The increase in red blood cell production from this drug will cause the blood to thicken. This side effect becomes even worse when the user is dehydrated. A bodybuilder taking diuretics before a show while taking EPO could run into major problems. This would be the same with an endurance athlete that doesn’t take in enough fluids during an event. When the blood becomes too thick, it has a hard time circulating through the body.

EPO is something that has been taken for decades to increase endurance. It stayed somewhat under the radar until some endurance athletes were recently accused of taking this drug to increase performance. The use of EPO is nothing new, and I doubt it will stop any time soon. As soon as a more advanced test is used to detect EPO, methods of passing this test will change.