"Certainly there are people out there who say testosterone replacement therapy is just wonderful, and others who say it doesn't do any good at all. What we're saying is we just don't know," said Dr. Dan Blazer of Duke University Medical Center, who led an Institute of Medicine probe of the therapy.
The report spotlights a huge area of contention, the claim that because testosterone levels slowly drop as men age, they undergo a male version of menopause — dubbed andropause by some doctors and drug companies — that requires treatment.
In fact, many doctors don't agree that andropause is a real phenomenon. Nor is there evidence that symptoms many older men report — such as decreased libido, frailty and fatigue — really are connected to testosterone when they could be inevitable consequences of aging, Blazer said.
Demand for prescription testosterone treatment by middle-aged and older men whose natural hormone levels are near normal is rising rapidly, the study found. More than 1.75 million prescriptions for testosterone products were written in 2002 — a 170 percent increase from 1999 — for an estimated 800,000 patients.
The Food and Drug Administration has approved testosterone therapy for men with hypogonadism, where the body makes very little testosterone. An estimated 4 million to 5 million Americans have hypogonadism, but only about 5 percent are thought to be getting treatment.
That means a lot of men using testosterone are in a gray zone.
And specialists hope the report's recommendations will help avoid the confusion that has plagued menopausal women, who once considered hormone replacement therapy a rite of passage until a major study recently declared that treatment too risky.
To help figure out how it should study the male hormone question, the National Institutes of Health asked its Institute of Medicine — which advises the government on scientific issues — to analyze just how much is known about testosterone therapy in older men.
Not much, concludes the report, to be released Wednesday.
Only a few studies have been done, all very small and lasting only months. That's far too little information to tell if testosterone offers any benefit to men who aren't markedly deficient in the hormone — much less if it's safe, concluded a panel of experts in hormones and men's health.
The chief safety concern is that boosting testosterone levels for long periods could spur the growth of prostate cancer, already a big risk as men age.
So the report recommends that the NIH begin a phased-in set of research studies to answer those questions:
- First, test a few hundred men for a year or two to see if testosterone therapy has benefits for older men who aren't markedly hormone-deficient, such as improving sexual function, muscle strength, cognitive function or quality of life.
- If those studies find possible benefit, then NIH should begin a major study of several thousand men followed for several years to prove those benefits and assess safety.
But some hormone specialists welcomed the advice.
"It's a very clever plan," said Endocrine Society spokesman Dr. William Rosner, a well-known testosterone specialist at the College of Physicians and Surgeons of Columbia University.
"We got burned a lot with women" for not having adequate science on hormone therapy before millions took it, Rosner noted.
For men, there's even less evidence on which to base a decision to boost waning hormone levels, or even to know what level is too low at what age, he added.
"Andropause, I don't know what that is," Rosner said, stressing that certainly men don't see an abrupt hormonal change, and associated symptoms, like women do during menopause. "I don't know who coined this word, but to my mind it's a disservice."
By Lauran Neergaard