A small study of female-to-male transsexuals shows that testosterone therapy at “male” dosages significantly increases bone mineral density.

While the female hormone estrogen is known to improve bone health in women, the findings raise the possibility that testosterone, at relatively low doses, might also have a similar benefit.

To examine the effects of testosterone therapy on the skeleton of genetic females, Dr. Vin Tangpricha, an endocrinologist from Emory University School of Medicine in Atlanta, and colleagues have measured bone mineral density at the hip and spine annually and monitored levels of sex hormones in 15 female-to-male transsexuals.

These participants are biologic females who suffer from gender dysphoria and take high doses of testosterone to change from the female to male body type, the team explains in the medical journal Clinical Endocrinology.

Over two years, male replacement testosterone therapy improved bone mineral density at the hip and maintained bone density at the spine. .

This improvement occurred despite lowered estrogen levels, the researchers note. During the study period, testosterone levels reached the upper normal range for males and estrogen levels declined to levels seen in postmenopausal females.

“The main question is whether women could see the same improvement on lower doses of testosterone or on testosterone analogs with less androgenic side effects,” Tangpricha told Reuters Health. “This needs to be explored in larger studies,” he added.

SOURCE: Clinical Endocrinology, November 2004.