Dopeology

One of the most commonly used forms of performance enhancement in endurance sports is the infusion of blood to increase the amount of oxygen-carrying red blood cells. An athlete may use for this purpose either his/her own blood - in which case the procedure is referred to as autologous blood transfusion - or the blood of someone else, known as homologous blood transfusion. Both procedures have advantages and disadvantages.

The advantages of autologous transfusion are that:

• One need not worry about donor compatibility
• Since one is using one’s own red blood cells detection is very difficult

The disadvantage is that one has to withdraw blood and store it for a period of time so that it will be available as required. The act of withdrawal significantly weakens an athlete, so the process cannot be performed any time near an important competition. It also alters certain physiological parameters in a way that may be detectable by the blood passport (see Bio-passport irregularities).

Homologous transfusion avoids these problems, but it is significantly easier to detect.

Homologous testing

Homologous blood transfusion is detected by a test that determines the presence of red blood cells of foreign origin. In addition to the well-known major blood types A, B, C, and O, and the Rh factors, which are determined by the presence or absence of certain protein molecules or antigens, red blood cells also may contain a number of other minor antigens.

The homologous blood test detects these antigens and, by using them as markers, it can be determined whether there is a homogeneous population of red blood cells present — as will be the case in anyone who has not had a blood transfusion from a foreign donor — or a heterogenous population, which is indicative of such a transfusion.

Autologous testing

There is no approved test for autologous transfusion currently in use.

One possible test is based on counting or quantitating the amount of red cells in the bloodstream, since any transfusion will increase this number. This test requires that the athlete breathe a small amount of carbon monoxide, which binds to red cells and thus acts as a tracer enabling them to be quantitated. However, carbon monoxide even in small doses may have deficits on performance, and thus this test has been opposed by athletes.

An alternative test for autologous transfusion is based on the presence of certain molecules commonly present in the bags in which blood is stored. A particular focus is the substance known as di-(2-ethylhexyl)phthalate or DEHP, used as a plasticiser to make the bags more pliant or flexible.

Several studies have shown that when an individual has a blood transfusion, significant amounts of DEHP are leached from the bag and enter the recipient’s blood stream. DEHP is subsequently metabolized, and several of its metabolites can be detected in the urine.

While DEHP is present in many other substances - and studies have shown that even individuals who have not received a blood transfusion generally test positive for these same metabolites - the levels are generally far higher following a recent transfusion. Thus it has been proposed that a urine test for these metabolites may be used to detect autologous blood doping.

This plasticiser test has not yet been officially approved for use however. In addition, DEHP-free bags are available and it seems likely that, now the test has been publicised, athletes using autologous transfusion will seek these DEHP-free alternatives.

Another alternative for detecting autologous blood transfusion is based on changes that occur in red blood cell membranes during storage. These changes might be detected either directly, through analysis of the red cells in an athlete, or indirectly, through changes in the metabolism that occur when the body recognizes and reacts to these altered cells.

Contributor: Andy Smith