Idiopathic hirsutism: Is it really idiopathic or is it misnomer?

Abstract

Hirsutism, which is characterized by excessive growth of terminal hair in a male pattern, may result from various causes including polycystic ovary syndrome (PCOS), non-classic congenital adrenal hyperplasia, adrenal or ovarian tumors or it may be idiopathic. Idiopathic hirsutism is currently defined as hirsutism associated with normal ovulatory function, normal serum androgen levels and normal ovarian morphology, however, the pathogenesis of idiopathic hirsutism is not clear. The androgens are the main hormones to stimulate growth of body hair, therefore, there should be any form of increased androgen effect irrespective of normal serum androgen levels in any patient with hirsutism. In accordance to this scientific truth, we have previously shown that, although within normal limits, patients with idiopathic hirsutism have relatively higher serum androgen levels (relative hyperandrogenemia) in comparison to healthy subjects which let as to think that is idiopathic hirsutism really idiopathic? In addition to relative hyperandrogenemia, we have previously shown that, in comparison to healthy subjects, women with idiopathic hirsutism demonstrated higher expression of steroid sulphatase and 17-beta hydroxysteroid dehydrogenase mRNA both in the subumbilical region and arm skin, which contributes to local androgen metabolism. Those results support the idea that, in some patients, although the adrenals or ovaries do not secrete increased amount of androgens leading to hyperandrogenemia, pilocebaceous unit locally produce increased amount of androgens leading to hirsutism without ovulatory dysfunction. Upon the demonstration of relative hyperandrogenemia and possible increase in local androgen synthesis in patients with idiopathic hirsutism, we think that idiopathic hirsutism is not idiopathic and it may be named as “normoandrogenic hirsutism”. Furthermore, it may not be a different entity but may be an early stage of hyperandrogenic disorders such as PCOS. Clinically, this can be find out by following-up patients with idiopathic hirsutism prospectively.

Keywords: Idiopathic hirsutism, Normoandrogenic hirsutism, Hyperandrogenemia, Androgen excess disorders

Core Tip: Idiopathic hirsutism (IH) is defined as hirsutism associated with normal ovulatory function, normal ovarian morphology and normal serum androgen levels, however, its pathogenesis is not clear. We have previously shown that, patients with IH have relatively higher serum androgen levels and demonstrated higher expression of steroid sulphatase and 17-beta hydroxysteroid dehydrogenase mRNA both in the subumbilical region and arm skin, which contributes to local androgen metabolism. Upon the demonstration of relative hyperandrogenemia and possible increase in local androgen synthesis in patients with IH, we think that idiopathic hirsutism is not idiopathic and it may be named as “normoandrogenic hirsutism”.