Postmenopausal bone loss at multiple skeletal sites: relationship to estrogen use.

Bone mineral content (BMC) was measured in the distal radius, proximal radius, and os calcis in 608 postmenopausal women, and the values were compared to vertebral osteoporosis and compression fractures determined radiographically, as well as to history of estrogen use. Current estrogen users had significantly higher BMC at all appendicular sites as compared to non-users. Prior estrogen users had lower appendicular BMC's than current users, but they were still significantly higher than non-users. However, radiographic assessment of the lumbar spine showed no difference in osteoporosis or compression fracture prevalence between prior users and non-users of estrogen, whereas current estrogen users had a significantly lower prevalence of osteoporosis in the spine. These findings suggest that estrogen effect on trabecular bone in the os calcis may be more transient than on cortical, appendicular bone. They also suggest that long term or permanent estrogen replacement is required to prevent spinal compression fractures.