Calcium Metabolism and the Menopause
In recent years attention has turned from the rather limited problem of vertebral crush fractures in postmenopausal women to a wider study of the effects of age on bone in general and is now turning to the specific role of the menopause in the light of the wider experience which has been gained. The ossifying effect of estrogens on the bone marrow of mice was shown to be similar to that in pigeons, and was also shown to be inhibited by testosterone. The loss of bone appears to be due to an increase in bone resorption rather than to a decline in bone formation, and its biochemical manifestations are reversible with estrogens. Until recently no biochemical differences involving calcium and phosphorus metabolism had been detected between pre- and postmenopausal women. The underlying mechanisms are only poorly understood, but present data are compatible with the concept that estrogens reduce the sensitivity of bone to the resorbing action of parathyroid hormone.