Growth Hormone a Top Target of Olympic Drug Testing
Published: Jul 17, 2012
By Todd Neale, Senior Staff Writer, MedPage Today
This year's Summer Olympic Games in London, which open on July 27, will likely see more drug testing than ever before, including tests looking for recombinant human growth hormone (rhGH).
According to a fact sheet, the International Olympic Committee (IOC) is planning on conducting about 5,000 tests, which tops the 4,770 performed at the 2008 Summer Games in Beijing. Testing has also been ramped up in recent years during the Winter Games.
The IOC takes control of testing Olympic athletes during the period of the Games, which this year started on July 16 -- when the Olympic village opened -- and runs until the closing ceremony on Aug. 12.
In anticipation of increased interest in anti-doping issues related to the Olympics, the Endocrine Society held a webinar to discuss the use of performance-enhancing drugs, with part of the focus on rhGH.
Not many professional athletes have been caught using the synthetic hormone, but in April, Patrick Mendes, a U.S. weightlifter with hopes of Olympic medals, admitted use and accepted a 2-year ban following two positive test results obtained in February, according to the U.S. Anti-Doping Agency (USADA).
Natural hGH produced by the pituitary gland comes in six or seven variants -- called isoforms -- although the synthetic version is almost entirely a copy of the 22-kilodalton (kDa) form, according to Alan Rogol, MD, emeritus professor of pediatrics at the University of Virginia in Charlottesville.
There is some 20-kDa rhGH being produced, but it's not nearly as prevalent, said Rogol, who co-wrote the part of the IOC's Encyclopedia of Sports Medicine on the endocrine system in sports and exercise.
Athletes take rhGH because it boosts energy, builds muscles, breaks down fat, and improves how the body looks. Some athletes take it with the belief that it allows the tendons and muscles to recover more rapidly from injury, allowing a return to hard training.
However, Rogol said, studies conducted in non-athletic populations have not supported much effect on sports performance, despite the effects on body composition. In general, the combination of rhGH and testosterone has been shown to be comparable to testosterone alone.
But there is an important caveat, he said. When athletes use rhGH unsupervised, it's unknown what substances -- and in what quantities -- they're taking, and what other performance enhancers they might be using also.
And smaller benefits that can't be captured in an experimental setting may make a huge difference for elite athletes. If a sprinter can add one-tenth of a second to his or her time, it could mean the difference between winning an Olympic medal or not even making it to the finals, Rogol said.
That could be why some athletes are willing to risk the side effects, including edema, arthralgia, and myalgia in the short term and effects on cardiovascular health and glucose tolerance in the long term.
To help keep all athletes on a fair level of competition, the IOC and various national agencies have introduced testing for a host of performance-enhancing drugs consistent with the World Anti-Doping Code. Testing for rhGH at the Olympic level was implemented for the 2004 Summer Games in Athens, Greece.
It isn't possible to detect rhGH in the urine. Rather, the predominant test is a measure of the ratios of the different isoforms in the blood. Testers look for an elevated ratio of the 22-kDa isoform in relation to all of the others. In normal populations, the ratio is about 0.6, but in cases of doping the ratio will likely be above 1 and can go as high as 6.
It's that test that caught the weightlifter Mendes.
"This case demonstrates yet again that the hGH test works to stop this dangerous drug from being used in sport," said USADA CEO Travis Tygart in a statement.
Outside of the period of the Olympic Games, USADA handles drug testing of U.S. athletes -- and foreign athletes competing in the U.S. -- both during events and at any other time of the year. Athletes are subject to both blood and urine testing at any time and in any place.
During the Olympic Games, the IOC tests all top-five finishers and two other random athletes in each competition.
This year, all samples will be tested at a laboratory accredited by the World Anti-Doping Agency at the GlaxoSmithKline facilities in Harlow, England.