NASHVILLE, TENN. — Suppression of androgens or estrogens increases bone turnover and bone loss in men, according to data presented at the annual meeting of the American Society for Bone and Mineral Research.
Gonadal steroid deprivation has been reported to increase skeletal sensitivity to the bone-resorbing properties of parathyroid hormone (PTH) in men. It's not clear whether this effect is due to the absence of estrogens, androgens, or both, said Dr. Benjamin Z. Leder, of Massachusetts General Hospital in Boston.
A total of 58 men, aged 20–45 years, were assigned to receive combinations of gonadotropin-releasing hormone (GnRH), an aromatase inhibitor, and hormone add-back therapy for 6 weeks, depending on their hormonal status.
Men in group 1 (16) received a GnRH analog, 3.6-mg goserelin acetate, given subcutaneously every 3 weeks, as well as an aromatase inhibitor, 5-mg anastrozole, given daily. These men were testosterone and estradiol deficient for the duration of the study. Men in group 2 (12) also received the GnRH analog and aromatase inhibitor, but testosterone was replaced with a testosterone gel (AndroGel), at 5 g daily. These men were testosterone sufficient and estradiol deficient. Men in group 3 (14) received the GnRH analog and aromatase inhibitor, but estradiol was replaced with an estradiol transdermal patch, applied twice weekly. These men were testosterone deficient but estradiol sufficient. Men in group 4 (16) received the GnRH analog, aromatase inhibitor, testosterone gel, and estradiol patch. These men were sufficient in both testosterone and estradiol and served as a control group.
All men underwent infusions of PTH (1–34) at baseline and at 6 weeks. Serum levels of the bone turnover marker cross-linked N-telopeptides (NTx) of type I collagen were measured during the infusions.
Mean NTx levels measured prior to PTH infusion did not change between baseline and week 6 in the control group, but NTx levels increased by 24% in group 1, by 16% in group 2, and by 11% in group 3. Serum NTx increased during PTH infusion in all groups at all time points.