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Anti-doping tests do not always identify cheating athletes

23 March 2009
Appeared in BioNews 500

New research has confirmed the inadequacy of current drug testing techniques used in sport to identify athletes using performance-enhancing drugs. The work, published in the British Journal of Sports Medicine, found that cheats from certain ethnic backgrounds are less likely to be caught.

The tests, which were initially introduced by the World Anti-Doping Agency (WADA) in 2004, analyse the relative levels of the naturally-occurring male hormone testosterone in urine samples from athletes compared to epitestosterone, a close derivative. Testosterone, and other hormones that boost testosterone levels, can be injected by athletes to enhance their performance. If the testosterone to epitestosterone ratio (T/E ratio) is more than four, it is taken as preliminary evidence of cheating and the sample is sent for further testing.

The team of scientists from the anti-doping lab near Lausanne, Switzerland, investigated the background hormone profiles of 171 football players from six different countries before and after adding extra testosterone. The footballers were aged between 18 and 36, and represented four groups: Africans, Asians, Caucasians and Latin-Americans.

They showed that some ethnic groups more frequently have a variant of the UGT2B17 gene, a gene affecting the excretion of testosterone, meaning that testosterone levels in their urine remain low. The results indicate that 81 per cent of the Asian players had this gene variant, compared to 22 per cent of the African, ten per cent of the Caucasian and seven per cent of the Latin-American players.

Christophe Saudan, lead researcher on the project, says: 'It means that some athletes can use testosterone without raising the T/E ration above four'. African athletes, for example, who rarely have the gene variant, excrete testosterone more efficiently: this makes them more likely to be caught if they cheat than their Asian counterparts.

Based on the findings, the scientists recalculated the test ratios to make them fair for each ethnic group. The found that more suitable T/E ratios were 3.8 for Asians, 5.6 for Africans, 5.7 for Caucasians and 5.8 for Latin-Americans. Even if these new ratios are applied, however, Saudan suggests that the test will still not be sensitive enough.

Saudan concludes that, based on the results from his lab, 'a unique and non-specific threshold to evidence testosterone misuse is not fit for purpose'. He suggests a solution to the problem could be the introduction of 'athlete's passports'; each individual's metabolic profile to be used as a baseline from which to monitor deviations to identify cheating. 'Each athlete would act as their own reference', he explained.

Frederic Donze, a spokesman for the WADA, says that the agency is well aware of the issue: 'The T/E ratio is just one of several warning signals that can lead to further action by anti-doping laboratories', he told New Scientist magazine, also confirming that work is currently underway to develop the 'athlete's passport' concept, including work with the Swiss group.

SOURCES & REFERENCES
Anti-doping test allows drug cheats to escape
New Scientist |  12 March 2009
Sport doping test is 'not fit for purpose' experts warn
The Daily Telegraph |  11 March 2009
Steroid doping tests avoid vital ethnic differences in hormone activity
EurekAalert |  11 March 2009
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