Does estrogen stimulate osteoblast function in postmenopausal women?

How estrogen therapy influences bone metabolism in postmenopausal women has previously been studied using several approaches, including bone densitome try, measurement of biochemical markers of bone turnover, and histomorphome try. Taken together, these investigations suggest that conventional doses o f estrogen protect from bone loss predominantly through suppression of bone resorption, with little evidence to suggest that a stimulatory action on o steoblasts is also involved. In contrast, studies of patients treated with estradiol implants suggest that, following prolonged exposure to relatively high estrogen levels, an additional stimulatory effect on osteoblast funct ion is observed. The suggestion that estrogen stimulates osteoblast activit y in postmenopausal women under certain circumstances is consistent with ot her evidence that estrogen is an important physiological regulator of osteo blast activity. Furthermore, these findings raise the possibility that it m ay be useful to develop strategies for treating postmenopausal osteoporosis that aim to reproduce the stimulatory action of relatively high estrogen l evels on bone formation in postmenopausal women. (Bone 24: 121-124; 1999) ( C) 1999 by Elsevier Science Inc. All rights reserved.