5α-dihydrotestosterone (DHT) is the strongest androgen in humans and is present in the blood in the fourth highest concentration following dehydroepiandrosterone (DHEA), androstenedione and testosterone. DHT is mainly produced by the microsomal enzyme 5α-reductase via testosterone. It is synthesised for example in prostate, skin, liver and hair follicles. Like testosterone, DHT is mainly present bound to sex-hormone-binding globulin (SHbG). DHT’s binding affinity to the androgen receptor is 2 to 5 fold higher than that of testosterone.
DHT is relevant for the male hair growth pattern and seems to be involved in the upkeep of the libido and the sexual functions of men.
Low testosterone and DHT levels occur in men with metabolic syndromes and/or diabetes type 2. Men with 5α-reductase deficiency have higher testosterone and lower DHT values, the external genitalia are not clearly pronounced. Increased DHT values are associated with hair loss (alopecia androgenetica). Women with hirsutism present increased DHT values.