Functional hyperandrogenism detected by corticotropin and GnRH-analogue stimulation tests in women affected by apparently idiopathic hirsutism

The etiologic diagnosis of hirsutism is often difficult. Previous studies h ave reported normal basal androgen and SHBG concentrations in 33-50% of hir sute women, suggesting the presence of an "idiopathic" form of hirsutism as the most frequent cause of this problem. The recent use of GnRH-analogues together with the corticotropin stimulation test allows better understandin g of whether the cause of hirsutism is androgen excess and, if so, whether the origin of the latter is ovarian, adrenal or both. The present study eva luated adrenal and ovarian function in 48 young hirsute women as well as in 78 normal women matched for body mass index and age, who acted as control group. To determine ovarian function, a single 100-mug dose of GnRH analogu e triptorelin was injected sc; thereafter, gonadotropins, 17-hydroxyprogest erone (17-OHP), Delta4-androstenedione (Delta4), total testosterone (T) and estradiol were determined. To better understand the adrenal function, 250 mug of 1,24 ACTH were administrated as iv infusion for 5 h, and plasma cort isol (F), 17-OHP, Delta4, DHEAS, T, 11-desossicortisol were measured. The c ombined use of these two stimulation tests was able to detect mild to moder ate abnormalities in the steroidogenesis of ovaries alone (23%), adrenals a lone (16.6%), or both (35.4%) in most hirsute women (75%) with otherwise no rmal baseline androgen concentrations. In particular, patients showed signi ficantly increased responses of 17-OHP, Delta4, total T, 11-desossicortisol , and F to 1,24-ACTH administration. Moreover, they also had significantly higher 17-OHP and T responses to triptorelin. In conclusion, milder forms o f functional ovarian and/or adrenal hyperandrogenism, similar to those foun d in clearly hyperandrogenic women, were observed and could be an underlyin g mechanism of idiopathic hirsutism. (J. Endocrinol. Invest. 24: 491-498, 2 001) (C) 2001, Editrice Kurtis.