Medicine continues to indulge Man's ancient quest for eternal youth, and one of those wannabe El Dorados is found in urology. Testosterone therapy (sometimes called androgen replacement therapy) has held out the promise of more vigorous twilight years for many men looking to turn back time. Unfortunately, they usually come away being reminded that stopping time is the province of tomorrow's quantum mechanics, and not today's medicine.

Testosterone, of course, is that hormone produced primarily in the testicles that makes a man clinically a man. It powers our sex drive, sperm production, red blood cell production, muscle strength, and facial/body hair. Our testosterone levels peak during adolescence and early adulthood, and so as we age, those levels decline.

We know that lower testosterone levels can (but not necessarily do) directly trigger a reduction in our sexual desire, self confidence, spontaneous erections, fertility, muscle strength and bone density. The ball that the Fountain-Of-Youthers are taking and running with is the notion that increasing their testosterone levels through supplements will reverse or stabilize these reductions.

Now, testosterone therapy is a proven treatment for hypogonadism, which is a disease in which the body is unable to produce normal amounts of testosterone due to a problem with the testicles or with the pituitary gland that controls the testicles. Doctors may prescribe testosterone as injections, pellets, patches or gels.

But would a similar regimen of supplementation taken by men with normal, healthy testosterone levels offset or reverse a decline? There has been relatively little testing done, and such trials as have been conducted have shown mixed results. Some of these results should be deal-breakers for would-be Ponce de León's, such as testicle shrinkage, enlarged breasts, noncancerous prostate growth, and even increased blood clot risk.

If you are still inclined to take the testosterone therapy plunge, see your doctor. She will measure your testosterone levels several times, and then provide you with a custom-tailored prognosis as to whether you might be a beneficiary of testosterone supplements.