Objective It is unknown whether long
term cross-sex hormone treatment affects the human skeleton. We monitored
bone mineral density and biochemical markers of bone turnover for 28-63
months in 20 male-to-female transsexuals (M-->F) treated with
anti-androgens and oestrogens, and 19 female-to-male transsexuals (F-->M)
treated with androgens. They underwent gonadectomy 13-35 months after the
start of cross-sex hormone administration.
Design Bone mineral density (BMD) and the
markers of bone turnover osteocalcin, alkaline phosphatase, fasting urinary
calcium/creatinine and hydroxyproline/creatinine, were measured at baseline,
after 1 year and after 28-63 months of cross-sex hormone administration.
Results In oestrogen-treated M-->F,
variables of bone turnover decreased significantly with consecutive
measurements. BMD had increased significantly after 1 year, but decreased
again to baseline levels after 28-63 months of cross-sex hormones. In
F-->M, alkaline phosphatase levels increased during the first year. BMD
did not change during the first year but had decreased significantly after
28-63 months following ovariectomy. In both M-->F and F-->M, the
change of BMD correlated inversely with serum LH and FSH levels. Of all
biochemical variables LH levels appeared to be the best predictor of loss of
BMD; in the long-term LH levels were more elevated in testosterone-treated
F-->M than in oestrogen-treated M-->F transsexuals.
Conclusion In M-->F, oestrogen treatment
prevented bone loss after testosterone deprivation. In F-->M the
testosterone dosage used, associated with a decline in serum oestradiol
levels, was unable to maintain bone mass fully in all subjects in the longer
term. The inverse relationship between BMD and serum LH levels suggests that
the dose of hormone replacement has been too low in subjects with a decline
in their BMD. Its cause might be underdosing or non-compliance in some
patients. We propose that serum LH levels may be used as a measure of the
adequacy of replacement with sex steroids.
Citation:
Clin Endocrinol (Oxf) 1998 Mar;48(3):347-54 an
article published on the Internet by PubMed
<http://www.ncbi.nlm.nih.gov/>