Prevalence of idiopathic hirsutism.

OBJECTIVE To evaluate the prevalence of idiopathic hirsutism in a large population of hirsute women. DESIGN 588 hirsute women (mean age 24+/-1, range 15-36 years) were evaluated as outpatients at the Department of Endocrinology of the University of Palermo, Italy. The diagnosis of idiopathic hirsutism was established in hirsute patients presenting regular ovulatory menstrual cycles and normal serum androgen levels (total testosterone, unbound testosterone and dehydroepiandrosterone sulfate). METHODS Hirsutism was calculated by the Ferriman-Gallwey-Lorenzo index. Serum androgens were evaluated in the follicular phase (days 5 or 6) and normal androgen ranges were calculated as the mean+/-2S.D. of serum levels of 30 ovulatory non-hirsute women. The presence of ovulation was determined by serum progesterone levels during the presumed luteal phase (days 21 or 22). All steroids were determined by specific RIAs. RESULTS 36 hirsute women (6%) had regular ovulatory cycles and normal androgen levels and were diagnosed as being affected by idiopathic hirsutism. CONCLUSIONS Idiopathic hirsutism is a relatively uncommon cause of hirsutism, affecting approximately 6%, of our population.