15 janvier 2007

No longevity benefit with growth hormone


PHILADELPHIA, Jan. 15 (UPI) -- Doctors said Monday their analysis of 31 scientific papers found that human growth hormone -- oft-touted as an anti-aging wonder -- does nothing to help a person live longer.

However, the papers do show that use of the expensive therapy has the potential to create adverse side effects.

"There is certainly no data out there to suggest that giving growth hormone to an otherwise healthy person will make him or her live longer," said Dr. Hau Liu, a research fellow in the Division of Endocrinology and in the Center for Primary Care and Outcomes Research at Stanford University School of Medicine in Stanford, Calif.

Liu and colleagues' conclusions will be published in Tuesday's edition of the Annals of Internal Medicine, the journal of the Philadelphia-based American College of Physicians.

"We did find that there was substantial potential for adverse side effects," Liu said, including such problems as joint swelling and pain, carpal tunnel syndrome and a trend toward increased new diagnoses or pre-diabetes. "You're paying a lot of money for a therapy that may have minimal or no benefit and yet has a potential for some serious side effects," Liu said. "You've got to really think about what this drug is doing for you."

"Growth hormone has been touted by people practicing fringe medicine for decades," Dr. Barry Horowitz, co-director of the Metabolic Research Institute in West Palm Beach, Fla., told United Press International. "They say growth hormone is an anti-aging therapy, can make your skin look better and improve your sex drive.

"But there is no proof -- as Dr. Liu has demonstrated -- that growth hormone does anything to extend a person's life," Horowitz said. "Our great fear is that in patients with occult, asymptomatic cancer, the administration of growth hormone may cause that cancer to grow and spread."

He said that growth hormone has been approved for treating children who have growth hormone deficiencies and to treat some adults with growth hormone deficiencies due to injury or disease to the pituitary gland.

"In many anti-aging clinics, growth hormone is prescribed willy-nilly off-label, without any proof that patients are better off," he told UPI. He also noted that the drug is highly expensive, and is not reimbursed for its off-label (unapproved) use.

Growth hormone is widely promoted on the Internet, and its use as a purported anti-aging drug has caught the attention of the popular media, ranging from the "Today Show" to Business Week. Between 20,000 and 30,000 people in the United States used growth hormone as an anti-aging therapy in 2004, a ten-fold increase since the mid-1990s, according to the authors of an unrelated study published in the Journal of the American Medical Association in 2005.

Growth hormone is naturally produced by the pituitary gland, a pea-sized organ at the base of the brain. Growth hormone is critical to proper development in children, particularly their height, and injections of growth hormone are considered a legitimate treatment for short children and for adults whose pituitary glands don't produce enough growth hormone to maintain normal metabolism. But most promoters of growth hormone as an anti-aging therapy target the healthy elderly.

Liu's team undertook a systematic review and analysis of published studies, excluding any that looked at diseases for which growth hormone is an accepted therapy. They focused solely on studies using growth hormone to treat the elderly, specifically those whose main maladies were nothing worse than age and being mildly to moderately overweight. They also included only studies that evaluated the use of the hormone in randomized, controlled clinical trials.

Of all the papers contained in two of the largest databases of medical literature in the world, only 31 met the team's criteria. The 31 studies had a combined total of slightly more than 500 participants, and the average duration of therapy was about six months, said Liu, adding that he was surprised at the limited amount of data in the literature.

"These studies were designed to look at what happens when you give growth hormone to a healthy elderly person," said Liu. "For example, what happens to their bone density, to their exercise levels and to their exercise capacity."

The researchers found that growth hormone had a modest effect on body composition, increasing lean body mass, or muscle, by slightly more than 2 kilograms and decreasing body fat by roughly the same amount.

But, Liu said, "It did not change other clinically important outcomes, such as bone density measurements, cholesterol and lipid measurements, and maximal oxygen consumption." In short, the studies provided no real evidence that the therapy resulted in increased fitness.

"From our review, there's no data to suggest that growth hormone prolongs life, and none of the studies makes that claim," said Liu.

Copyright 2007 by United Press International. All Rights Reserved.

Inutile de se précipiter vers des produits miracles qui ne présentent aucune justification scientifique et qui ont probablement des effets secondaires.

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