Treatment of primary hyperparathyroidism with cyclofenil--a synthetic stilbestrol derivative with minimal feminizing effects.

In eight patients with primary hyperparathyroidism (HPT) the laboratory effects of cyclofenil, which is a synthetic stilbestrol derivative with weak feminizing effects, were studied over a period of 5-13 weeks. In all the patients there were during treatment clear reductions of the serum calcium levels as well as the urinary excretions of calcium and hydroxyproline. These findings are in accordance with earlier reports that oestrogens reduce bone resorption mediated by parathyroid hormone. It has previously been demonstrated that cyclofenil can be given, on other indications, for several years to both male and female patients without oestrogenic side-effects. This pilot study, therefore, indicates that treatment with cyclofenil might be of value in some cases of primary HPT where surgery is not considered.