Abstract
Ethinylœstradiol was administered to 10 post-menopausal hyperparathyroid patients. There was a gradual fall in the fasting plasma-calcium and urine-calcium and in the 24-hour- urine calcium and hydroxyproline, which was maintained up to one year in the patients who continued therapy. Œstrogen treatment of hyperparathyroidism in post-menopausal women might be expected to prevent bone disease by inhibiting bone resorption, and stone disease by reducing urine-calcium.