Natural resistance to testosterone testing

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In the NYT, Gina Kolata reports on a study that found that a substantial number of athletes show negative results on urine tests for testosterone, even when they're doping:
The 55 men in a drug doping study in Sweden were normal and healthy. And all agreed, for the sake of science, to be injected with testosterone and then undergo the standard urine test to screen for doping with the hormone.

The results were unambiguous: the test worked for most of the men, showing that they had taken the drug. But 17 of the men tested negative. Their urine seemed fine, with no excess testosterone even though the men clearly had taken the drug.

It was, researchers say, a striking demonstration of a genetic discovery. Those 17 men can build muscles with testosterone, they respond normally to the hormone, but they are missing both copies of a gene used to convert the testosterone into a form that dissolves in urine. The result is that they may be able to take testosterone with impunity.


Men with the gene deletion still metabolize testosterone, Dr. Schulze says. But, she adds, she does not know where the hormone goes. "We have no idea," she said. "That's what we're trying to find out."

If you've got this gene deletion, you've potentially got an enormous advantage in terms of being able to dope without getting caught. Even for those who don't have the gene deletion, I wonder whether there's some chemistry you could use to force testosterone metabolism down whatever alternate pathway is involved here (or alternately to disable the standard pathway), producing a masking effect for even those with normal genetic profiles.


It's actually even worse. You have the opposite problem if you have two functional copies of UGT2B17--a false positive test:

"14% of those with two functional copies of the gene were over the detection threshold before they had even received an injection. The researchers estimate this would give a false-positive testing rate of 9% in a random population of young men."

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