Aetiology

The most common cause are

• polycystic ovarian syndrome (PCOS) – around 72% of women with clinical hyperandrogenism have PCOS (1)
• idiopathic - androgen levels are not increased, resulting from hypersensitivity of the hair follicle to androgen (2). There may be a raised level of peripherally derived androgens such as 3 alpha-androstanediol glucorinide. The condition usually begins in the early teens and increases with age. A family history may be present.

Other causes:

• adrenal -
  • non-classic congenital adrenal hyperplasia (less than 5%)
  • congenital adrenal hyperplasia
  • Cushing's syndrome
  • virilizing tumour
• pituitary -
  • acromegaly
  • hyperprolactinaemia (1)
• ovarian -
  • virilising tumours
  • gonadal dysgenesis
• thyroid dysfunction (1)
• iatrogenic -
  • drugs - androgenic drugs, oral contraceptives, phenytoin
• menopause – is thought to be due to decreasing oestrogen levels leading to unopposed androgen effects, most present with facial hirsutism (4)
• Turner's syndrome

Reference:

• (1) Al Robaee A et al. Update on hirsutism. Acta Dermatovenerol. 2008;17(3):103-19
• (2) Rosenfield R.D. Hirsutism. NEJM 2005; 353:2578-2588
• (3) Hunter MH, Carek PJ. Evaluation and treatment of women with hirsutism. Am Fam Physician. 2003;67(12):2565-72
• (4) Clark C. Advising women with hirsutism. The pharmaceutical journal 2008;280