The effect of ethinyl oestradiol on calcium and bone metabolism in peri- and postmenopausal women.

The effects of ethinyl oestradiol on plasma and urinary calcium and other indices of bone turnover have been compared in peri- and postmenopausal women. In postmenopausal women ethinyl oestradiol caused significant decreases in the fasting plasma total and ionised calcium and phosphate concentrations, in alkaline phosphatase activity and in the fasting urinary Ca/Cr and OHPr/Cr ratios. Similar, but less marked, effects were observed in peri-menopausal women, with significant decreases in the fasting plasma phosphate and urinary Ca/Cr ratio. Small decreases in the plasma total and ionised calcium concentrations, in alkaline phosphatase activity and in the urinary OHPr/Cr ratio also occurred but were not statistically significant in our sample. Ethinyl oestradiol therefore appears to reduce bone loss in peri- as well as post-menopausal women, at least in the short term, but the effect is less pronounced in the former group.