Abstract
Sequential measurements of metacarpal cortical thickness show that premenopausal women as a group neither gain nor lose bone but that postmenopausal women (whether after artificial or natural menopause) lose approximately 1% per annum. Significantly reduced loss was observed with oestrogen therapy. There is no correlation between the rate of loss and dietary calcium in subjects on normal diets but the rate in those subjects on low calcium diets was significantly faster than in 12 subjects on calcium supplements. In postmenopausal women with spinal osteoporosis the rate of bone loss is more than twice that of the controls. This rate of loss is significantly reduced by treatment with large doses of vitamin D. The effectiveness of vitamin D therapy is related to the effect of the therapy on calcium absorption.