Human Growth Hormone

Andy Pettitte of the New York Yankees speaks to the media about his human growth hormone use on Feb. 18, 2008, at Legends Field in Tampa, Fla.

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Like EPO, human growth hormone (hGH) occurs naturally in the body. In fact, the pituitary gland, the pea-sized organ located at the base of the brain, produces hGH to stimulate growth in children and adolescents and to increase muscle mass in adults. As soon as synthetic hGH became available as a prescription medication in 1985, when the U.S. Food and Drug Administration approved its use for a number of diseases that retard growth or cause muscle deterioration, athletes began eyeing it as a doping agent. They figured it could mimic the muscle-building effects of anabolic steroids. At first, the high cost of the medication discouraged widespread use as a PED, but, as the saying goes, where there's a will to win, there's a way. The 1996 Olympic Games have been called the "hGH Games" because of the rampant use of the drug among competitors.

Today, athletes get hGH from a variety of sources: doctors who are willing to write prescriptions for off-label use, Internet pharmacies, illicit Web sites for performance-enhancing drugs and clinics that use the hormone to reverse the effects of aging. A few even turn to black-market dealers that collect hGH from human cadavers. It's a risky gamble, especially considering the lack of scientific evidence to suggest that hGH actually increases athletic performance. Oh, and don't forget the side effects. Using hGH has been linked to a variety of medical conditions, including joint pain, muscle weakness, fluid retention, carpal tunnel syndrome, cardiomyopathy and hyperlipidemia [source: Mayo Clinic].