Dopeology

EPO, or erythropoietin, is a naturally occurring hormone that stimulates the production of red blood cells. It functions to maintain the proportion of red cells in the blood stream, known as the hematocrit, at a fairly stable level.

EPO was originally developed to treat people with anaemia, particularly that resulting from kidney disease. Since EPO is synthesised primarily in the kidneys, its production is curtailed in such patients, and their haematocrit can fall to dangerously low levels.

For athletes however, EPO can be used to raise haematocrit above natural levels, and thus provide a substantial performance boost in any kind of event where endurance is important.

Testing

Since EPO is naturally found in the body, it is difficult to test for. Initially, before a reliable test was developed, the UCI - the governing body of professional cycling - established a maximum allowable haematocrit of 50%. While this does not prevent doping with EPO, or with blood transfusions, it does create a limit to these practices.

Subsequently an EPO test was developed that takes advantage of slight structural differences between the natural form and the synthetic form, both of which are excreted in the urine. These differences result in different electrical charges on the two types of EPO, so that in an electrical field they can be separated. However this separation is complicated by the fact that both natural and synthetic forms of EPO are not homogeneous. That is, they consist of a group of similar but slightly different molecules. Each type of molecule behaves slightly different in an electrical field, so distinguishing natural from synthetic involves judging the patterns these different molecules make.

While patterns that are considered definitely indicative of the presence of synthetic EPO can be identified, the test probably has a very large number of false negatives: patterns that are judged to be solely natural EPO despite the high likelihood of the presence of some synthetic EPO.

To make detection even more complicated, in the past few years several new versions of EPO have been developed that frequently require their own test.

One of these newer versions, CERA, is a longer-acting substance, and has become increasingly popular with athletes. The test for CERA, though different from that for the original synthetic EPO, is based on the same general principle of charge separation.

Contributor: Andy Smith