DHT is a byproduct of testosterone. Testosterone is a hormone which influences many aspects of behavior, from sex drive to aggression.
Testosterone is converted into DHT by an enzyme produced naturally in various parts of the body called 5-alpha reductase.
DHT is found in several body organs, most notably in hair follicles and the prostrate gland.DHT causes susceptible hair follicles to miniaturize and ultimately disappear.
Endocrinologists state that there are no useful effects of DHT in the adult male.
Most people have read that eunuchs, who can't produce testosterone because they've been castrated, don't lose their hair even if they are genetically disposed to baldness. Interestingly, if a castrated man is given testosterone, he begins losing hair if he is genetically predisposed to baldness.