Study Discloses Hormone Tie to Aging Process

Growth hormone supplements might slow some effects of aging on the body, building muscle mass, decreasing fat and thickening the skin, according to a short-term study of 21 older men being published in today’s New England Journal of Medicine.

“The effects of six months of growth hormone on lean body mass and (fat) tissue mass were equivalent in magnitude to the changes incurred during 10 to 20 years of aging,” wrote the researchers led by Dr. Daniel Rudman of the Medical College of Wisconsin in Milwaukee.

Because atrophy of muscle and skin contributes to the fraility of many elderly people, Rudman and his colleagues speculated that some older people might benefit from growth hormone supplements.

But they cautioned that such treatments are not the fountain of youth. The long-term effects of the supplements are unknown and they are unlikely to benefit organs such as the brain, eyes, heart or lungs. In addition, they would cost more than $10,000 a year.

The study, one of the few of its kind, concluded that diminished amounts of growth hormone are responsible, at least in part, for the decrease in muscle mass, increase in fat and the thinning of skin that occur in old age.

“This is a very preliminary finding,” Dr. Axel G. Fuller of the Chicago Medical School, a co-author of the study, told the Associated Press. “We are not ready to recommend growth hormone for all of the aging people of the world.”

The elderly most likely to be the target of further tests are severely ill patients, who might receive the supplements to build up their strength before or after surgery.

The researchers administered growth hormone injections to 12 healthy men, age 61 to 81, who had diminished concentrations of the hormone in their blood. The injections were given three times a week for six months.

The men treated with growth hormone had an 8.8% increase in lean body mass, a 14.4% decrease in fat and a 7.1% increase in skin thickness, the researchers found. No significant changes in lean body mass, fat or skin thickness were seen in a control group of nine men who did not receive the injections.

But they cautioned that the 12 men also had small but significant increases in blood pressure and blood sugar levels.

Growth hormone is a naturally occurring human protein that can be produced in large quantities through genetic engineering techniques. It is most commonly used to prevent dwarfism in children deficient in the hormone. But most specialists do not recommend its use in healthy individuals for other reasons, such as for short children who are not growth hormone deficient.

About one-third of all men 60 to 80 years old have diminished concentrations of growth hormone, while two-thirds have concentrations of the hormone similar to those in younger men. The reasons for these differences are not known.

The researchers said that their results “cannot be generalized” to men with normal concentrations of growth hormone or women of similar age. Because they were not included in the study, additional experiments would have to be conducted to learn the effects of growth hormone supplements in older women.

The Rudman study and other related small studies “should be considered preliminary,” said Dr. Mary Lee Vance of the University of Virginia in a New England Journal editorial on the article.

Vance said that long-term growth hormone supplements might contribute to health problems such as diabetes, arthritis, high blood pressure and heart failure. These are important ethical issues, particularly when growth hormone use is being contemplated for otherwise healthy older adults.

It is also uncertain whether the injections actually improve muscle strength and exercise capacity in the elderly, or simply increase the amount of muscle tissue.

The treatment regimen used by Rudman “would cost approximately $13,800 a year,” Vance said.

She concluded: “Because there are so many unanswered questions about the use of growth hormone in the elderly and in adults with growth hormone deficiency, its general use now or in the immediate future is not justified.”