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 have reported normal basal androgen and SHBG concentrations in 33-50% of hirsute 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 understanding 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 evaluated 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-μg dose of GnRH analogue triptorelin was injected sc; thereafter, gonadotropins, 17-hydroxyprogesterone (17-OHP), Δ4-androstenedione (Δ4), total testosterone (T) and estradiol were determined. To better understand the adrenal function, 250 μg of 1,24 ACTH were administrated as iv infusion for 5 h, and plasma cortisol (F), 17-OHP, Δ4, DHEAS, T, 11-desossicortisol were measured. The combined use of these two stimulation tests was able to detect mild to moderate abnormalities in the steroidogenesis of ovaries alone (23%), adrenals alone (16.6%), or both (35.4%) in most hirsute women (75%) with otherwise normal baseline androgen concentrations. In particular, patients showed significantly increased responses of 17-OHP, Δ4, 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 of functional ovarian and/or adrenal hyperandrogenism, similar to those found in clearly hyperandrogenic women, were observed and could be an underlying mechanism of idiopathic hirsutism.