Testosterone doping test "not fit for purpose"
Italy's Christian Moreni was arrested at the 2007 Tour de
France after he failed a doping test for testosterone. (Keystone)
Anti-doping authorities should abandon a key test used to catch drug cheats because it fails to take into account vital ethnic variations, according to Swiss researchers.
Scientists at Lausanne's anti-doping laboratory claim that tests
commonly administered to top-tier athletes to detect testosterone should
be replaced by a system that tracks a competitor's biological patterns.
The study, published in the British Journal of Sports Medicine, claims
the test is "not fit for purpose". It was funded by Fifa, football's
international governing body, and carried out by scientists at the World
Anti-Doping Administration (Wada).
Testosterone is a naturally occurring hormone but experts say it is widely used as a steroid in synthetic form to enhance performance among athletes.
Researchers in the French-speaking city examined the testosterone levels of 171 football players in six different countries after steroids were deliberately added to their urine samples.
They reported "significant differences" after performing a chemical analysis of the steroid profiles of 57 Africans, 32 Asians, 50 Caucasians and 32 Hispanics.
The study found levels were naturally highest among Hispanic players, who on average produced marginally more testosterone than Africans and Caucasians and significantly more than Asians.
Testosterone is a naturally occurring hormone but experts say it is widely used as a steroid in synthetic form to enhance performance among athletes.
Researchers in the French-speaking city examined the testosterone levels of 171 football players in six different countries after steroids were deliberately added to their urine samples.
They reported "significant differences" after performing a chemical analysis of the steroid profiles of 57 Africans, 32 Asians, 50 Caucasians and 32 Hispanics.
The study found levels were naturally highest among Hispanic players, who on average produced marginally more testosterone than Africans and Caucasians and significantly more than Asians.
" Even if we apply different thresholds we will not be sensitive enough
in the detection of testosterone and we have to use another system. "
Christophe Saudan, Wada researcher
Christophe Saudan, Wada researcher
"Not fit for purpose"
"These results demonstrate that a unique and non-specific threshold to
evidence testosterone misuse is not fit for purpose," the study's
authors said.
The problem is that ethnic groups have different variations of a gene called UGT2B17, which influences how quickly testosterone is expelled from the body in urine.
Under Wada rules, any ratio of testosterone to epitestosterone greater than 4:1 is considered evidence of possible doping and leads to further tests to look for synthetic testosterone. The normal ratio in healthy males is 1:1.
But the genetic variations skew those ratios. The researchers said the baseline thresholds are actually 5.8:1 for Hispanics, 5.7 for Caucasians, 5.6 for Africans and 3.8 for Asians, the group most likely to secrete the least testosterone into urine.
Wada, which accredits drug-testing labs around the world, said it was "well aware" of the issue of ethnic variations. It said suspicious results are "just one of several warning signals" and are followed up by carbon-isotope tests that are not influenced by genetic factors.
Wada spokesman Frederic Donze also said the agency has been working with the Lausanne lab for more than three years on developing an athlete passport program.
"This approach ... will allow anti-doping organisations to monitor variations in the athlete's biological profile and subsequently target-test or sanction based on abnormal variations," he said.
"This detection strategy is not affected by genetic variations."
The problem is that ethnic groups have different variations of a gene called UGT2B17, which influences how quickly testosterone is expelled from the body in urine.
Under Wada rules, any ratio of testosterone to epitestosterone greater than 4:1 is considered evidence of possible doping and leads to further tests to look for synthetic testosterone. The normal ratio in healthy males is 1:1.
But the genetic variations skew those ratios. The researchers said the baseline thresholds are actually 5.8:1 for Hispanics, 5.7 for Caucasians, 5.6 for Africans and 3.8 for Asians, the group most likely to secrete the least testosterone into urine.
Wada, which accredits drug-testing labs around the world, said it was "well aware" of the issue of ethnic variations. It said suspicious results are "just one of several warning signals" and are followed up by carbon-isotope tests that are not influenced by genetic factors.
Wada spokesman Frederic Donze also said the agency has been working with the Lausanne lab for more than three years on developing an athlete passport program.
"This approach ... will allow anti-doping organisations to monitor variations in the athlete's biological profile and subsequently target-test or sanction based on abnormal variations," he said.
"This detection strategy is not affected by genetic variations."
Ethnic variations
The ethnic variations, the study said, make it impossible to apply a
universal benchmark for testosterone doping. Scientists instead have
called for the introduction of a passport system, which measures
variations in individual athletes.
"Even if we apply different thresholds we will not be sensitive enough in the detection of testosterone and we have to use another system," said Christophe Saudan, a researcher with the Lausanne lab. "Now we have to turn to the biological passport, which takes into account the individual range of the athlete.
"The athlete is his own reference. We have to look at the athlete's reference rather than a population reference."
The passport system would measure an athlete's baseline blood and urine profiles against numbers gleaned from subsequent tests. Such "longitudinal" controls wouldn't necessarily look for specific substances, but could detect changes in body chemistry that would indicate use.
Jiri Dvorak, Fifa's chief medical officer, said of more than 25,000 doping tests carried out each year between 2004-08 in world football, just 51 were positive for anabolic steroids. He acknowledged there were ethnic differences.
Dvorak, a member of Wada's health, medical and research committee, said he would submit the study to the panel's next meeting in Montreal, Canada, in September.
The chairman of the IOC's medical commission, Arne Ljungqvist, said the research confirmed what was already known by anti-doping experts but did not cast fresh doubt on previous positive tests.
swissinfo with agencies
"Even if we apply different thresholds we will not be sensitive enough in the detection of testosterone and we have to use another system," said Christophe Saudan, a researcher with the Lausanne lab. "Now we have to turn to the biological passport, which takes into account the individual range of the athlete.
"The athlete is his own reference. We have to look at the athlete's reference rather than a population reference."
The passport system would measure an athlete's baseline blood and urine profiles against numbers gleaned from subsequent tests. Such "longitudinal" controls wouldn't necessarily look for specific substances, but could detect changes in body chemistry that would indicate use.
Jiri Dvorak, Fifa's chief medical officer, said of more than 25,000 doping tests carried out each year between 2004-08 in world football, just 51 were positive for anabolic steroids. He acknowledged there were ethnic differences.
Dvorak, a member of Wada's health, medical and research committee, said he would submit the study to the panel's next meeting in Montreal, Canada, in September.
The chairman of the IOC's medical commission, Arne Ljungqvist, said the research confirmed what was already known by anti-doping experts but did not cast fresh doubt on previous positive tests.
swissinfo with agencies
http://www.swissinfo.ch/eng/Specials/International_year_of_chemistry/Health_&_Research/Testosterone_doping_test_not_fit_for_purpose.html?cid=645318
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