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Caution Urged on Testosterone Therapy

Panel: More research needed on safety, efficacy of popular hormone

WEDNESDAY, Nov. 12, 2003 (HealthDayNews) -- There simply is not enough scientific evidence to support the pumped-up use of testosterone among middle-aged and older men.

That's the conclusion of a new Institute of Medicine (IOM) report, which also calls for more clinical studies on the use of testosterone, particularly among men 65 and older.

"We were struck by the paucity of placebo-controlled clinical trials that have examined the efficacy and risk of testosterone therapy in treating men," Dr. Dan Blazer, chair of the IOM committee that wrote the report, said at a news conference Wednesday.

There have been only 31 small trials in the older age group, most of which had fewer than 50 participants; only one lasted more than a year.

Yet the report also points out that almost 2 million prescriptions for testosterone were written in 2002, a 30 percent increase from 2001 and a 170 percent increase from 1999. No doubt that number will be even higher for 2003, noted Blazer, who is also a professor of psychiatry and behavioral sciences at Duke University Medical Center in Durham, N.C.

"We live in a society where people are really looking for an anti-aging drug, and this is a very popular candidate," Blazer said. "We think the scientific community and individuals who are receiving these products need to be thinking more carefully at it."

There is a certain logic to viewing testosterone, a hormone, as a possible fountain of youth. Levels do decrease with aging. Possible benefits include improvements in strength, cognitive functioning, and sexual function. Potential risks, however, might include clotting and increased risk of prostate cancer.

Still, the U.S. Food and Drug Administration (FDA) has approved the hormone only for a limited number of conditions, notably hypogonadism, a condition marked by inadequate production of testosterone.

It seems clear, then, that "off-label" use must account for the rapid upsurge in recent years.

"We did not specifically say that the FDA should try to censor that type of prescription, but we do feel that the very large number of prescriptions that are being written currently across the life cycle -- coupled with the fact that it only has limited approval -- means, almost certainly, most of these prescriptions are not being written for hypogonadism," Blazer said.

The rise in the use of testosterone is no doubt also fueled by the increase in the number of approved testosterone products. In the past, a monthly intramuscular injection was the only way to administer the hormone. Today gels and patches, which are also more efficient at maintaining levels, are available, said Dr. E. Darracott Vaughan Jr., chairman emeritus of the department of urology at Weill Medical College of Cornell University in New York City and a member of the committee.

New studies should start by looking at the potential benefit of this type of therapy, the report recommended.

"We are interested in both the benefits and risk of testosterone therapy. But it's not worth putting up with any risk if there's absolutely no benefit, so our approach was to first try to prove there were some benefits," said Dr. Deborah Grady, another committee member and a professor at the School of Medicine of the University of California San Francisco.

It's easiest to see a benefit if you start with the group that is most likely to benefit: men 65 and older who have documented low testosterone levels and symptoms that might be related to those low levels.

The report also recommended looking at testosterone as a therapy rather than as a preventive measure because the evidence of any preventive benefit, Blazer said, "is almost nil."

If small studies show a benefit, then researchers can proceed to large-scale trials.

The committee acted purely in an advisory capacity, Blazer said. The report has already been delivered to the National Institute on Aging (NIA), which will now decide what it plans to do.

The NIA, which requested the study along with the National Cancer Institute, "commended" the report in a statement today and noted that it would "consider the IOM recommendations very carefully, including options for implementing the type of trials suggested in the IOM report."

The report carries an interim message for physicians and patients as well. "In many ways our report is saying, 'Pay attention to what we know and what we don't know and make decisions accordingly,'" Blazer said.

More information

To access the full report on testosterone and aging, visit the National Academies Press. The National Institute on Aging has more on getting older.

SOURCES: Nov. 12, 2003, teleconference with Dan Blazer, M.D., professor of psychiatry and behavioral sciences, Duke University Medical Center Durham, N.C.; Deborah Grady, M.D., professor, School of Medicine, University of California, San Francisco; E. Darracott Vaughan Jr., M.D., chairman emeritus, department of urology, Weill Medical College, of Cornell University, New York; National Institute on Aging statement; Institute of Medicine report, Testosterone and Aging: Clinical Research Directions
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