DHT may not be to blame for men's prostate problems.

The use of dihydrotestosterone (DHT) in older men doesn't appear to have an effect on prostate growth, though it does decrease spinal bone mineral density, according to research published in the Nov. 16 issue of the Annals of Internal Medicine.

Amanda Idan, of the University of Sydney in Australia, and colleagues analyzed data from 114 men older than 50 without known prostate disease who were randomized to receive daily transdermal DHT or placebo gel for two years. The primary efficacy end point was total prostate volume measured by ultrasonography every six months.

The researchers found that subjects' total and central prostate volume increased, but DHT had no beneficial or adverse effect on prostate growth. DHT treatment was associated with decreased bone mineral density in the spine (by 1.4 percent) but not the hip. There were no serious adverse effects caused by DHT.

"Idan and colleagues argue that their findings provide insight about the potential efficacy of future synthetic androgen receptor modulators that will likely share (with DHT) the anabolic effects on muscle and fat, as well as the sparing effects on the prostate. However, we caution that each synthetic androgen-receptor modulator could have a different target organ profile. We conclude that DHT acts as a hormone in tissues without high concentrations of 5α-reductase enzymes but mainly in an autocrine-paracrine manner in tissues like the prostate, in which 5α-reductase is abundant," write the authors of an accompanying editorial.