Blood Doping: From Iron to Gold?

An international expert in testing methods to detect “blood doping” in athletes led a Meet-The- Expert session on Sunday morning. Carlo Brugnara, M.D., Director of Clinical Chemistry at the Children’s Hospital in Boston, reviewed recent developments in the laboratory detection of blood doping in sports. It has long been known by athletes that an increased red cell mass can result in increased performance. Athletes in some sports utilize blood doping to enhance performance by several methods. Currently, the most common (and allowable) practice is high altitude training. Probably the most effective way to do this, stated Dr. Brugnara, is to “live high” (at higher altitudes) and “train low” (at lower altitudes).

Another method of blood doping is the transfusion of allogeneic or autologous blood, as either fresh or stored red cells, in order to boost oxygen transport delivery and ability to increase oxygen consumption during performance. This practice has been long been in existence. The recent implementation of an assay now enables authorities to identify athletes who have transfused themselves with allogeneic blood. This is accomplished by phenotyping the blood for some of the minor red cell antigens to see if two different populations of red blood cells are present.

A more recent method of blood doping is to inject a recombinant erythropoietic agent. The Australian Institute of Sports, in preparation for the Olympic Games that took place in Sydney, took a lead role in developing testing algorithms for two models of possible erythropoietic agent use and conducted confirmatory testing in those athletes identified by the algorithms. One such model is an “off model,” which is used to screen for athletes who may have injected EPO over an interval sometime prior to (but not near) the date of testing. This model uses five laboratory parameters: hgb level, reticulocyte count, serum erythropoietin level, serum transferring receptor level, and percentage of macrocytic red cells. These values, along with a serum ferritin (to screen for very high levels that would indicate use of parenteral iron, which is commonly administered along with the erythropoietic agent by athletes), can serve as a “hematologic passport,” which is obtained by testing athletes repetitively over a period of time, in order to identify athletes who are using an erythropoietic agent.

The second model is an “on model,” in which an algorithm is used to screen for athletes who are using an erythropoietic agent at the time of testing. This model can be difficult to differentiate for athletes who are utilizing high altitude training, since the algorithm includes a combination of increased hgb level, decreased reticulocyte count, and decreased erythropoietin levels (all of which are also present in athletes training at high altitudes). Athletes who fit this profile therefore need a confirmatory urine test that distinguishes between the presence of native erythropoietin or the presence of a recombinant erythropoietic product, by virtue of their differing glycosylation profiles. This assay can also identify athletes who have used a recombinant erythropoietic agent within three days of the date of testing.

Finally, testing has been implemented to detect athletes who may be using artificial oxygen carriers such as bovine or human hemoglobin solutions. It is not currently known whether athletes have access to or are utilizing these agents, but based on the sad history of extensive use of other blood doping techniques, sports authorities have had to use a considerable amount of creativity in order to stay a step ahead of athletes in their quest of gold.