Androgen physiology and the cutaneous pilosebaceous unit.

Hormones play an important role in cutaneous physiology. The androgen hormones are of particular relevance in modulating hair growth and sebum production in the pilosebaceous unit, which is comprised of the hair follicle and sebaceous gland. Testosterone arising from the circulation is converted peripherally to its more potent, reduced form, dihydrotestosterone, by the enzyme 5 alpha-reductase. Dihydrotestosterone is primarily responsible for androgen receptor binding and exerting end-organ effects. The clinical sequelae of enhanced local androgen production include androgenetic alopecia, hirsutism, and acne. These disorders can be fraught with significant psychosocial ramifications because of their highly visible nature and impact on perceptions of masculinity and femininity.