Nov. 12, 2002 (Washington) -- Growth and sex hormones are all the rage these days for the treatment of everything from a bulging waistline to sexual dysfunction, but they are "not ready for prime time" and in fact could have serious side effects, according to the lead author of a report in this week's edition of the Journal of the American Medical Association.
"At this juncture, for anti-aging use, growth hormone should be 100% limited to controlled clinical trials," said Marc R. Blackman, MD, of the National Institutes of Health, at a news conference.
It isn't known how many people are taking growth hormone supplements, but anecdotal evidence suggests that many people in their 40s and 50s are taking it in hopes of preventing various conditions of aging. But there is not sufficient research to suggest that it will have a positive effect, said Blackman.
The current study followed healthy men and women between the ages of 65 and 88 as they received one of three combinations: growth hormone plus a sex steroid (estradiol and progesterone for women, testosterone for men); growth hormone plus a placebo; or a sex steroid plus a placebo.
There were encouraging results: fat body mass decreased significantly in both men and women taking either GH alone or GH with the sex hormones. The study also found that in both men and women taking GH in combination with the sex hormone, lean body mass (muscle) increased significantly.
But "disappointingly," Blackman said, the researchers did not find any significant increase in strength as measured by a weightlifting test. In women, strength was unaffected by either GH treatment or the sex hormone treatment, whether alone or in combination therapy. In men, on the other hand, treatment with GH plus testosterone only marginally improved strength.
Still, the reduction in fat mass and gain in lean mass is an encouraging effect.
But there were several adverse side effects in both men and women taking GH therapy including swelling (edema), joint pain, and carpal tunnel syndrome. Of greatest concern, however, was the "very high frequency" of glucose intolerance or diabetes, Blackman said. These conditions appeared in 18 of the men who received growth hormone versus only seven who did not receive it.
All of the side effects went away a few weeks after hormone treatment ended, but most people who take growth hormone stay on it for a long time, said Blackman. Asked whether long-term exposure to growth hormone could lead to diabetes, he responded, "That's a fair summary."
It is not yet known whether the beneficial effects last beyond the end of hormone therapy. Blackman said future trials will try to answer that question.
Similar increases in lean mass and decreases in fat mass can also be achieved through exercise, but some patients may be incapable of exercise due to a medical or psychological condition. Hormone therapy could offer a way to "mimic" exercise, he added.
The study raised interesting questions that could be the basis for future research. The subjects of this trial were all healthy, but many researchers believe that older people who are on the verge of becoming frail might stand to benefit the most from hormone treatment. Others with special conditions might benefit as well, such as patients about to undergo a hip replacement. But these and other questions will have to be answered by further research.