Idiopathic hirsutism--an ovarian abnormality.

We investigated increased production of testosterone and androstenedione in 44 women with unexplained adult-onset hirsutism, 41 of whom had normal-sized ovaries. Twenty women in this group had at least 50 per cent suppression of plasma testosterone and androstenedione after four to five days of dexamethasone. Testosterone and androstenedione values in ovarian-vein effluents were higher than those of their adrenal veins. We calculated adrenal secretion rates of both androgens in each patient by relating the adrenal gradients to those of cortisol. In 42 of the hirsute women, including those whose androgens were suppressed after dexamethasone, the ovaries were the predominant source of androgen production. The women with dexamethasone suppression had milder degrees of virilism and lower production rates of testosterone and androstenedione. We conclude that the ovaries are the source of excessive androgens in most women with unexplained hirsutism, and that corticoid-suppressible patients have milder forms of ovarian hyperandrogenism.