Hirsutism is excessive androgen-dependent male-pattern terminal hair growth in females. In contrast, hypertrichosis refers to an increase in nonsexual (non-androgen dependent) vellus hair growth. Hirsutism occurs in areas where high levels of androgen are required for hair growth, such as the upper lip, chin, chest, upper back, stomach, and thighs. The condition affects 5%-10% of individuals of childbearing age.

Hirsutism may be idiopathic, or it may be linked to other conditions. Familial hirsutism is generally facial with a prolonged preauricular hair line. Other etiologies can be considered on the basis of the organ causing the abnormality. Adrenal hirsutism may be due to congenital adrenal hyperplasia or hypercorticism. Causes of increased cortisol include primary nodular hyperplasia, adrenal adenoma, and adrenal carcinoma.

Ovarian hirsutism can be due to polycystic ovary syndrome (PCOS) or ovarian tumors. Pituitary hirsutism is associated with Cushing disease, a prolactin-secreting adenoma, and psychotropic medications that increase prolactin (ie, antipsychotics). Ectopic hormone production, such as the production of ACTH by small cell lung cancer or HCG by choriocarcinoma, also leads to hirsutism. Anabolic steroids lead to the condition as well.

Hirsutism may be associated with seborrhea, acne, and androgenetic alopecia (termed SAHA syndrome). These findings can also be seen in PCOS; however, in SAHA, menstrual cycles are not anovulatory and ovarian ultrasound is unremarkable. HAIR-AN syndrome has also been characterized, which is marked by hyperandrogenemia, insulin resistance, and acanthosis nigricans.