Dihydrotestosterone (DHT) is made from testosterone by an enzyme called 5-alpha reductase. It can also be made from DHEA, a hormone more common in women. DHT is found in skin, hair follicles, and the prostate. The actions of DHT and the sensitivity of hair follicles to DHT is what causes hair loss.
DHT also acts in the prostate. Without DHT, the prostate doesn’t develop normally. With too much DHT, a man can develop benign prostate hypertrophy, also known as an enlarged prostate.