Follicle-stimulating hormone not shown to regulate postmenopausal bone resorption
ASBMR Annual Meeting
TORONTO — Suppression of follicle-stimulating hormone does not decrease bone resorption, according to a study of postmenopausal women presented at the American Society of Bone and Mineral Research 2010 Annual Meeting.
“There has been a question of whether the bone loss that occurs following menopause is a function of the estrogen being lost or whether it is a function of the follicle-stimulating hormone level being increased,” Matthew Drake, MD, PhD, an endocrinologist and assistant professor of medicine at Mayo Clinic College of Medicine, Rochester, Minn., told Endocrine Today.
In vitro studies have shown that an increase in bone resorption during menopause is due to not only loss of estrogen but to increases in follicle-stimulating hormone (FSH). This prompted Drake and colleagues to examine the impact of FSH suppression in healthy postmenopausal women.
The researchers randomly assigned 21 women to suppression of endogenous FSH secretion with leuprolide 7.5 mg, a gonadotropin-releasing hormone agonist, administered intramuscularly for 28 days, as compared with 20 women assigned to placebo injections. The duration of treatment was 4 months. All women also received aromatase inhibitors to avoid any endogenous estrogen variability that may confound the study results, Drake noted.
According to the results, women assigned to leuprolide had about 90% suppression of their FSH levels into the premenopausal range. Using bone resorption markers CTX and TRAP5b as measures of bone resorption, the researchers observed that women with suppressed FSH at 4 months also had slight increases in serum CTX and TRAP5b, similar to increases observed in the control group, according to Drake.
“There was no difference in bone resorption between women with high FSH levels and women with low FSH levels,” Drake said.
Given the results of this study, targeting FSH as a means of limiting bone loss in postmenopausal women is not likely to be an effective intervention strategy for limiting postmenopausal bone loss, Drake concluded. – by Louise Gagnon
For more information:
- Drake M. Concurrent oral session 23: Osteoporosis pathophysiology – regulators of bone remodeling. #1133. Presented at: American Society of Bone and Mineral Research 2010 Annual Meeting; Oct. 15-19, 2010; Toronto.
The study clearly shows that a reduction in gonadotropins in not enough to stimulate resorption, but, rather, it is the fall in the level of estrogen. This was suggested in previous data, for which we dropped gonadotropins with the use of gonadotropin-inhibiting substances for the treatment of endometriosis or fibroids. The fall in FSH and luteinizing hormone resulted in profound bone loss due to the estrogen deficiency. The same thing occurs in anorexia nervosa or with pituitary tumors. There is little doubt that the absence of estrogen is the major cause of the loss of bone in the menopause, not the rise in FSH and luteinizing hormone.
– Robert Weinstein, MD
Director, Bone Histomorphometry Lab,
University of Arkansas for Medical Sciences
Center for Osteoporosis and Metabolic Bone Disease
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