Science and sensibility

With my job interview done with and my last ever lab report safely stowed within the hand-in box I have time again write posts for this blog and do a few of the other things I do when not completely snowed under by work. One of those things I'm really keen about is the sport of cycling, so I marked the controversy surrounding Tyler Hamilton’s positive test for blood doping with interest.

The higher the percentage of red blood cells in an athlete’s blood the easier it is for that athlete to supply his muscles with oxygen. Athletes have tried to artificially raise this percentage – called the hematocrit percentage – to increase their endurance since at least the 1970s. In the simplest form of such blood doping, which the USA men’s cycling team has admitted to using in the 1984 Olympic Games, an athlete has about one litre of blood taken from them and frozen a few months before a major competition. In the mean time the athlete’s bone marrow produces more red blood cells to replace the ones sitting in his freezer, restoring their hematocrit number to somewhere near the average of 45%. When the big competition comes around the stored blood, and all the red blood cells it contains, are injected back into the athlete’s blood - raising his hematocrit percentage by as much as 10%. It is not presently possible to test if this sort of blood doping has occurred and instead cycling’s governing body the UCI tests racer’s hematocrit levels and makes anyone with a level above 50% stand down for 15 days.

One of the problems with this form of blood doping is that the initial taking of blood leads to anaemia (which actually means lack of red blood cells) making it hard for the athlete to train until their hematocrit returns to normal. To avoid this athlete’s have been known to receive transfusions drawn from people with the same blood type. In fact, a Spanish cyclist last year admitted that under team orders he had a family member take EPO (a hormone that stimulates the production of red blood cells) so he could transfuse their blood into his sytem and increase his hematocrit.

But now Australian scientists have developed a way to test if an athlete (or anyone else) has recently had a blood transfusion. The test compares 200 different proteins that lie on the surface of red blood cells. These cell surface proteins contribute to a blood typing very much more refined than the familiar ABO system. If an athlete’s blood contains red blood cells displaying a mixture of these refined blood types then it can be taken as evidence that they have had a blood transfusion.

Tyler Hamilton became the first athlete to be caught out by this test in this years Olympics (where he one a gold medal in the time trial) and Vuelta a Espana (Tour of Spain.) Hamilton will keep his Olympic medal because the “B sample” required to convict him of blood doping wasn’t properly handled and as a result produced an inconclusive result. His two positive tests from the Vuelta leave the UCI and the International Olympic Committee in the embarrassing situation of having an Olympic champion who has turned in 3 positve tests in the space of a month, one of them at the Olympics.

Hamilton continues to protest his innocence and claims to be gathering a crack team of haematologists to discredit the test that has condemned him. I for one really do want to believe him, after all this is the man who finished the Tour de France fourth with a broken collar bone, wore his dead dog’s collar during this year’s tour as a mark of respect and swore on his wife that he was doing it all clean.