Growth hormone: Tough to detect, predict effects

Our bodies naturally produce it. Physicians sometimes prescribe it. So why did Major League Baseball recently suspend 13 players for using it and the National Football League players' union tentatively agree to testing for it?

Human growth hormone is the performance enhancer of the moment.

On Aug. 5, the Yankees' Alex Rodriguez and the Phillies' Antonio Bastardo were among the players suspended for obtaining synthetic growth hormone from Biogenesis of America, a Florida clinic that shut down in December. Rodriguez has appealed his suspension.

Since the 1980s, athletes have used injections of human growth hormone without a legitimate medical need, in violation of international sporting rules and federal law.

Compared with steroids, there are fewer side effects, and tests are less likely to return positive. But some clinical studies cast doubt on whether growth hormone improves athletic performance at all, and because the response varies from person to person and day to day, predicting the effects is not easy.

Nature provides its own model for understanding the side effects, says John Kelly, an orthopedic surgeon at the Hospital of the University of Pennsylvania. Patients with a condition known as acromegaly release too much growth hormone from the pituitary gland, situated just beneath the brain. They have a threefold increased risk of premature death, grossly enlarged physical features, and problems with nerves, joints, and muscles.

"So even though people who take growth hormone may look bulkier for a while," Kelly said, "the biologic clock still accelerates. It comes at a price later in life."

Growth hormone reduces fat, repairs injuries, and builds muscle - at least in normal physiology.

But that doesn't necessarily mean that extra growth hormone raises batting averages. In 2008, a review of 44 studies concluded that, when used in healthy young adults, growth hormone causes a leaner body but no change in strength.

Studies on athletes are particularly scarce. The Mitchell Report, written in 2004 by former U.S. Sen. George J. Mitchell of Maine, cites anecdotal evidence from athletes who said growth hormone "didn't/doesn't work for them." But at least one study shows that, when growth hormone is combined with steroids, the body-composition changes in athletes may be greater.

In certain cases, the need for growth hormone is legitimate. The FDA allows prescriptions for people with naturally low levels, such as dwarf children or adults with rare pituitary tumors. Certain intestinal problems and muscle wasting associated with HIV can also be treated with growth hormone.

Most patients obtain the hormone from endocrinologists, says Rahul Kapur, a family medicine doctor at Penn. Patients use pens with the active ingredient to inject themselves daily or weekly, depending on the brand. Monthly costs range from $500 to $3,000, which is more expensive than a monthly steroid supply, Kapur said.

Soccer player Lionel Messi is the rare case of a legitimately medicated athlete. The Argentine soccer player was diagnosed with growth hormone deficiency at the age of 11. When Argentinian teams declined to foot his medical bills, Messi joined FC Barcelona. Now 5-foot-7, he is a three-time FIFA World Player of the Year.

"It's very much an underground thing, so it's hard to get a feel for what's going on," said Barry Kenneally, a sports medicine doctor at the Rothman Institute at Thomas Jefferson University Hospital. He estimates that 1 percent of Americans use illicit performance enhancers - especially athletes, bodybuilders, and adults concerned with aging.

Since Major League Baseball started random drug testing in 2002, steroids have lost favor to growth hormone, according to the Mitchell Report. Because only a minuscule amount of growth hormone is excreted in urine, blood tests are done instead. And the two available tests aren't so reliable. The body degrades growth hormone in less than 30 minutes, so the most widely used test only detects injections within 12 to 24 hours.

Other performance enhancers banned by the MLB include stimulants like amphetamines and sedatives like marijuana.

Testing of Olympic athletes for growth hormone started in 2004. This year, MLB became the first major professional league to test for it.

The National Football League and its players union have tentatively agreed to test 40 blood samples for human growth hormone each week of the season and suspend violators for four games, according to a memo from the NFL Players Association reported last week.