Effect of prednisone on plasma testosterone levels and on duration of phases of the menstrual cycle in hyperandrogenic women.

A group of 106 women of reproductive age with laboratory and clinical evidence of hyperandrogenism was treated with prednisone. The daily dosage varied between 7.5 and 10 mg. Ovulatory activity was assessed prior to and during therapy by basal body temperature and observation of changes in the cervical os and cervical mucus. Plasma testosterone levels were significantly suppressed by prednisone therapy. This was associated with initiation of ovulatory activity in 5 of 14 (35.7%) amenorrheic patients and 10 of 11 (90.9%) anovulatory patients. In 81 ovulatory patients, prednisone therapy resulted in statistically significant shortening of the follicular phase and lengthening of the luteal phase of the menstrual cycle. The mean length of the menstrual cycle was unchanged. Significant correlations between percentage suppression of plasma testosterone and shortening of the follicular phase or lengthening of the luteal phase were observed. Suppression of plasma testosterone by prednisone was maximal after 2 months of treatment, while the effect on the phases of the menstrual cycle was progressive with duration of treatment. The effects of prednisone at daily dosages of 7.5 or 10 mg were not significantly different. These results suggest that prednisone therapy in hyperandrogenic women exerts an effect on both phases of the menstrual cycle, possibly related to suppression of plasma testosterone levels.