This assay is useful for the diagnosis and differential diagnosis of Hyperandrogenism specially when used in conjunction with measurement of other sex steroids. It is an adjunct in the diagnosis of Congenital adrenal hyperplasia. Dihydrotestosterone is an endogenous androgen sex steroid and hormone. The enzyme 5?-reductase catalyzes the formation of DHT from testosterone in certain tissues including the prostate gland, seminal vesicles, epididymides, skin, hair follicles, liver, and brain, and is crucial in the development of male characteristics and reproductive function.