What was being hailed as one of the greatest rides in Tour de France history turned into a nightmare for Floyd Landis when his urine sample showed elevated levels of testosterone.
Landis initially defended himself by saying that his body naturally
produces high levels of testosterone. According to Dr Shuaib Manjra,
chairman of the South African Institute for Drug-Free Sport, previous
samples would also have shown elevated testosterone levels had Landis'
body produced it naturally.
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In addition, it was argued that alcohol consumed the evening before the
test, or cortisone injections that Landis was taking for a hip problem,
may also have been responsible for the elevated testosterone levels.
According to Dr Manjra, these excuses are not viable either.
How the testing works
The T/E test
The standard test athletes undergo for testosterone doping is called a
T/E test. This test measures the ratio between the two hormones:
testosterone and epitestosterone. The result is expressed as a T/E ratio
(testosterone/epitestosterone.)
Ratios of about 1/1 are considered normal. Because of the potential for
individual variation, the World Anti-Doping Association considers scores
of 4/1 or higher to constitute a positive test. Landis' sample showed a
ratio of 11/1.
This test does however deliver some false positives, and some athletes
have successfully contested positive results. This is why additional
tests are sometimes required.
Note that a test score of lower than 4/1 does not necessarily prove
innocence. In some cases athletes, like some of those implicated in the
Balco scandal, use epitestosterone along with testosterone in order to
balance the T/E ratio and mask their testosterone use. In such cases a
high concentration of the two hormones in urine samples can suggest a
doping violation.
The T/E ratio test is usually performed on two urine samples (the A and
B samples).
The CIR test
A third step in the testing process is to conduct a carbon isotope ratio
test (CIR). This test is both more expensive and more labour intensive
than a T/E test, which is why it is usually only used as a second line
of testing. Rarely, it is however used as a first-line test - the recent
testing of US sprinter Justin Gatlin is an example of this.
The CIR test is used to distinguish between natural and synthetic
testosterone by measuring levels of the isotopes carbon 12 and carbon
13.
Synthetic testosterone contains lower levels of carbon 13 than those
naturally occurring in the body.
In the case of Floyd Landis, both the T/E tests and the CIR test yielded
positive results.
Since the test results have been made known the arguments in defence of
Landis have shifted away from the science to attacks on the French laboratory
where the tests were conducted and alleged irregularities in the testing procedure.
Challenges remain
According to Dr Manjra there is a lot of doping going on and much of it
goes undetected.
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