Androgenic hair loss is due to the activity of androgens, predominantly DHT, at the dermal papillae of the individual follicles. In adult men, its incidence is roughly equivalent to chronologic age, and it has a strong genetic component.
The physiology is primarily androgenic, with dihydrotestosterone (DHT) the major contributor. Androgens are important in male sexual development around birth and at puberty. They regulate sebaceous glands, apocrine hair growth and libido. With increasing age, androgens stimulate hair growth on the face,