Is idiopathic hirsutism idiopathic?

Background: Hirsutism is the excessive growth of terminal hair in a male pattern in a female. In most hirsute women, hirsutism is caused by increased androgens. However, not all women with hirsutism actually show elevated levels of circulating androgens with standard laboratory tests, in which case we speak of idiopathic hirsutism (IH). Objectives: The aim of this paper is to investigate whether there are biochemical markers that can be used to unravel the cause in IH. Methods: An electronic search through the PubMed database was conducted to find studies describing potential biomarkers for IH. Results: The majority of included studies claimed an increased 5α-reductase (5α–RD) activity in women with IH by means of increased DHT metabolite levels. Studies investigating abnormalities of the androgen receptor (AR) and serum levels of indirect markers showed no significant differences. Conclusions: Our literature search showed that polymorphisms of the AR as well as indirect markers seem to be nonspecific, but that the dihydrotestosterone-reduced metabolite 5α-androstane-3α,17β-diol glucuronide is markedly enhanced in women with IH, suggesting an increased 5α–RD activity in these women. Further studies need to be performed to determine the clinical usefulness of 3α-diol G as a biomarker for IH.