This test measures serum concentrations of dihydrotestosterone and is closely related to those of testosterone. 5 alpha-dihydrotestosterone is the most potent naturally occurring androgen, is produced from testosterone through the action of cholestenone 5 alpha-reductase. DHT is responsible for the development of the male external genitalia and the prostate. It is also primarily responsible for the physical changes that occur during male sexual maturation. Elevated levels may indicate hypergonadism or hirsutism.