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 reatment
with exogenous growth hormone (GH) affects several markers of
bone formation and collagen turnover in healthy adults, according
to new findings published in the April issue of The Journal
of Clinical Endocrinology and Metabolism. The persistence
of these effects after GH is discontinued may therefore be useful
in detecting GH abuse in athletes, Dr. Luigi Sacca of University
Federico II in Naples, Italy, and colleagues with the GH-2000
Study Group suggest.
The investigators
examined the effects of GH therapy on biochemical markers of
bone and collagen turnover in 99 healthy volunteers. The subjects
were randomized to either placebo or GH, at 0.1 IU/kg per day
or 0.2 IU/kg per day, for 28 days. This was followed by a 56-day
wash-out period.
Levels
of all of the biochemical markers studied were increased relative
to baseline and placebo in GH-treated patients at 21 days. Moreover,
these effects were dose-dependent. Many of these "GH-induced
changes in the bone and collagen markers persist long after
GH withdrawal," the researchers found. In particular, significant
increases in procollagen type III and osteocalcin were still
detected on the last day of the study.
Dr. Sacca's
group suggests that these changes "may provide a reasonable
basis on which to devise a robust test for GH doping."
Another
important study finding is that men are more sensitive than
women to the effects of GH on bone and collagen turnover, which
is consistent with "the current opinion that GH-deficient
women must be treated with higher GH doses than men." The
fact that this gender difference remained even at high doses
of GH also suggests "there is a gender-related difference
in the bone responsiveness that cannot be easily reversed by
increasing the GH dose."
This new
research appears to pave a solid path for implementing detection
procedures to a performance substance that has previously been
undetected. Exactly how and when it could be implemented remains
to be seen as well as what the athletes do to defeat this potential
new detection method.
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