COUNTERPOINT: Estrogen Effects on Calcitropic Hormones and Calcium Homeostasis

Aresearcher evaluating the relative importance of the various calcitropic hormones in bone and calcium disease might conclude that estrogen would be a good contender for the most clinically significant hormone in view of its role in the pathogenesis of osteoporosis. Paradoxically, it is not usually considered a calcitropic hormone because there are no rapid detectable effects on extracellular calcium homeostasis. It is this subtle nature of estrogen action that makes its study difficult. However, estrogen is recognized as a hormone with perhaps the most profound effect of any hormone on the female skeleton. Bone loss at the menopause is preventable for up to 10 yr by estrogen replacement (1). If estrogen treatment is not introduced, it has been estimated that 11% of the bone loss in a 70-yr-old woman is menopause related (2). If estrogen plays a substantial role in age-related bone loss, this could rise to 29% of the skeleton.