GH, Sex Steroids Should Be Confined to Controlled Trials

Laurie Barclay, MD

November 12, 2002

Nov. 12, 2002 — Growth hormone (GH) alone or in combination with sex steroids should not be used outside of controlled trials, according to the results of a study reported in the Nov. 13 issue of The Journal of the American Medical Association. These drugs increase lean body mass and decrease fat mass, and increase cardiovascular endurance a little in older men, but there are significant adverse effects.

"Although this study suggests that GH or related substances, particularly given in combination with testosterone in older men, may one day be a promising therapeutic agent in the treatment of certain age-related conditions, it is not ready for prime time," lead author Marc R. Blackman, MD, from the National Institutes of Health in Bethesda, Maryland, says in a news release. "There is much that we still don't know about its efficacy and, more importantly, there are too many known and potential adverse consequences associated with it. It is a fascinating and promising area of research, but at this time we can't recommend it for use outside of a carefully controlled and monitored clinical trial."

In this randomized, double-blind, parallel-group trial, 57 healthy men and 74 healthy women, aged 65 to 88 years, were divided into eight groups. Men received recombinant human growth hormone (hGH) plus placebo testosterone, testosterone plus placebo hGH, hGH plus testosterone, or placebos for both hGH and testosterone. Women received hGH plus placebo estrogen and progestin (HRT), HRT plus placebo hGH, hGH plus HRT, or placebos for both hGH and HRT.

After 26 weeks of treatment, both men and women had significant increases in lean body mass and decreases in fat mass after treatment with hGH. Men treated with both hGH and testosterone had greater improvements in these measures than did those who were treated with either hormone alone. Men who received both drugs also had improved cardiovascular endurance. This effect was not evident among older women treated with hGH, HRT, or the combination. There was no clear effect of treatment on muscle strength in men or women.

Adverse effects of treatment were reported in up to 40% of subjects, especially in men and women who received hGH alone or in combination with sex steroids, and adverse effects were generally more frequent and severe in men. Arthralgias occurred in 41% of the men taking hGH but in none of the women, and carpal tunnel symptoms occurred in 32% of the men taking hGH plus testosterone but in none of the women.

Transient glucose intolerance or diabetes developed in 18 men treated with hGH, in seven men not receiving hGH (P=.006), and in none of the women. However, edema developed in none of the men, in 39% of the women taking hGH alone, and in 38% of the women taking hGH plus HRT. All adverse effects resolved two to six weeks after treatment was discontinued.

Although sex differences in beneficial and adverse effects of hGH could have been partly due to dosage, because dose was determined by body weight, subsequent studies suggest that women need higher doses of hGH to elicit a physiological response similar to that in men.

"This study makes the important point that because adverse effects were common in response to GH administration, individuals, particularly those who are elderly, should not use hGH outside of controlled investigational studies. GH has not yet been demonstrated to be of clinical utility as an anti-aging intervention," says Stanley Slater, MD, deputy director of the National Institute on Aging's Geriatrics and Clinical Gerontology Program. "Nonetheless, there were significant changes in body composition and cardiovascular endurance, which were augmented by the addition of testosterone in men. This remains an interesting area for further research."

He warned that these supplements are expensive, their benefits largely unproven, and the risks of cancer with long-term use are still unknown.

JAMA. 2002;288:2282-2292

Reviewed by Gary D. Vogin, MD

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