A new study has found that testosterone replacement therapy (TRT) improves bone strength and muscle mass in older men who have low testosterone levels and may help prevent osteoporosis.

Testosterone therapy has been used to improve bone strength and muscle mass in some men. However, the hormone treatment is controversial, because it has been associated with increasing the risk of prostate cancer and high levels of red blood cells and its other effects are not fully known.

Now, in one of the first clinical trials involving men over 60-85 years of age, the preliminary results have indicated that testosterone treatment for five months has a positive effect on the bone markers of older men.

This is the first known study to report on the impact of bone metabolism based on dosing schedules.

For the study, lead author E. Lichar Dillon, of the Department of Internal Medicine at the University of Texas Medical Branch in Galveston, and colleagues studied 13 men, ranging in age from 60 to 85.

During the five-month trial, the men were either given weekly injections of testosterone, weekly injections of testosterone every other month, or a placebo.

The researchers found that men receiving testosterone had reduced bone turnover, compared with men on a placebo.

While the effects of testosterone therapy over the long term aren't clear, the researchers said they believed the treatment would be beneficial by preserving bone mass and preventing osteoporosis.

"These preliminary data show beneficial effects of testosterone therapy on bone turnover markers in older men with low-to-normal testosterone concentrations using both continuous and monthly cycled testosterone replacement," Dillon said.

"The effects of sex hormones on markers of bone formation are complex, but this is an important step in understanding how the process works," Dillon added.

The results were presented at the 121st Annual Meeting of the American Physiological Society.