Effects of hormone deficiency, androgen therapy and calcium supplementation on bone mineral density in female transsexuals.

A total of 79 healthy female transsexuals, divided into four groups, were involved in this study. Group 1 comprised 15 pre-operated normal cycling females; Group 2, five pre-operated females who were on regular androgen therapy for 1-3 years; Group 3, 27 post-operated females who were on regular androgen therapy for 2-12 years; and Group 4, 32 post-operated females who either had stopped or were on irregular androgen therapy. A bone scan of the lumber spine, at positions L2-L4, was carried out for each subject. A blood sample was taken for measurement of plasma testosterone concentrations. Ten subjects from Group 3 had a repeat bone scan following 10-39 months of calcium supplement (625 mg daily as calcium carbonate); another 10 post-operated females of Group 3 had a repeat bone scan 6-59 months later; and five subjects from Group 4 had a repeat scan following resumption of regular androgen therapy for 17-27 months. The mean +/- SE concentrations of testosterone of Groups 1-4 were, respectively, 0.58 +/- 0.05, 10.1 +/- 2.48, 7.7 +/- 0.98 and 0.99 +/- 0.14 ng/ml. Pre-operated females (Group 2) following 1-3 years of regular androgen therapy had significantly higher BMD and age-matched BMD than corresponding levels in pre-operated normal cycling females in Group 1. While the age-matched BMDs of post-operated females, who were on regular androgen therapy, were not significantly different, the mean BMD was significantly lower than corresponding values in the controls of Group 1. Post-operated females in Group 4 had significantly lower BMDs and age-matched BMDs as compared to corresponding values in controls of Group 1. The BMDs and age-matched BMDs of post-operated females, who were on regular androgen therapy, were significantly raised following daily calcium supplementation for durations ranging from 10-39 months. A repeat bone scan carried out following a lapse of 6-59 months did not reveal any significant change in the BMDs and age-matched BMDs of 10 post-operated females on regular androgen therapy. On the other hand, the BMDs and age-matched BMDs of post-operated females in Group 4 were significantly raised following the resumption of regular androgen therapy for 17-27 months. Results of the present study showed that ovariectomy and remaining in the hormone-deficient state for a sufficiently long duration was associated with a definite loss of bone mass. However, it was shown in this study that the resumption of regular androgen therapy for a sufficient duration could arrest this loss and, additionally, substantially increase the bone mass. Androgen appears to have a potentially greater impact on bone mass than oestrogen. Furthermore, calcium supplementation in a Singaporean population, which is accustomed to a low dietary calcium intake, can assist in the accretion of a higher bone mass in an adult population.