ObjectiveHirsutism results from hyperandrogenemia and/or exaggerated androgen responsiveness. Among various causes of hirsutism, some patients do not exhibit androgen excess which is called idiopathic hirsutism (IH). The pathogenesis of IH could not so far be clearly established.DesignTo investigate the mRNA expression of aromatase enzyme and the other enzymes having functional roles in the steroidogenic pathway, in freshly obtained skin tissue from subumbilical skin and the arm of the patients with IH and healthy women.MethodsTwenty-one women with IH and 15 healthy women were included in the study. We aimed to determine mRNA expressions of genes associated with local androgen synthesis and metabolism (CYP11A1, STS, CYP19A1, SRD5A1, SRD5A2, HSD3B1, AR, COMT, ESR1, ESR2, HSD3B2, CYP17A1, SULT2A1, SULT1E1, HSD17B2, IL6, TGFB1, TNFA) from skin biopsy and blood samples of patients with IH and the data compared with healthy subjects.ResultsPatients with IH exhibit significantly lower interleukin 6 (IL6) mRNA expression and higher steroid sulphatase (STS) and hydroxysteroid (17beta) dehydrogenase 2 (HSD17B2), gene mRNA expression, respectively, in the subumbilical region skin biopsies. Similarly, patients with IH exhibit significantly lowerIL6mRNA expression and higherSTSandHSD17B2gene mRNA expression, respectively, in the arm skin compared to healthy women's subumbilical region.ConclusionsIn both arm and subumbilical skin biopsy of patients with IH, we observed an up-regulation ofHSD17B2andSTS, decreasedIL6mRNA expression, probably determining an increase in the local amount of active androgens, which could then be used as substrate for other androgen metabolic routes.