Estrogen and progestin effects on urinary calcium and calciotropic hormones in surgically-induced postmenopausal women.

Seventeen surgically-induced postmenopausal (PM) women were randomized to receive either 0.625 mg of conjugated estrogens (CE) daily or 150 mg of intramuscular depomedroxyprogesterone acetate (DMPA) every 3 months. Urinary calcium/creatinine ratios were significantly higher than ratios of premenopausal controls before treatment, but were lower in all patients 2 months after both types of treatment. Compared to controls, all PM patients had similar levels of serum PTH and 25 hydroxy vitamin D before and after treatment. As a group, PM patients had lower levels of 1.25-dihydroxyvitamin D. In 5 patients who had levels which were below the normal range, 3 were treated with CE and 2 received DMPA. These patients all had significant increases in 1,25-dihydroxyvitamin D after treatment. Serum calcitonin did not change with either CE or DMPA treatment. These data suggest that, while both CE and DMPA lower calcium excretion in PM women, the mechanism(s) for the effects of hormonal treatment on bone resorption remain unsettled.