(DHT) The most active male sex hormone or androgen; formed in target tissues from testosterone (which is the main form of androgen circulating in the blood). Testosterone must be converted to DHT before it can do its job (the enzyme for which is 5-alpha reductase, and a deficiency of which is a cause of intersex.

A state of intersex in which the karyotype is male (i.e. 46,XY), the gonads are testes (hence also male), but the body is completely unresponsive to testosterone and to its metabolite dihydrotestosterone, so it develops in the female way, with a normal vulva and vagina apparent at birth, and with normal development of the breasts at puberty. Because the testes still secrete anti-Mullerian hormone, there's no uterus. Invariably these children are raised as girls, normal except for their primary amenorrhea and their infertility. Specialist medical supervision is needed, because there is an increased risk of cancer in the abnormal gonads. Synonymous with androgen insensitivity syndrome (complete form).

The main male sex hormone, or androgen, in the blood (where it is measured as serum testosterone). Secreted in large amounts by the testis in a man. Before it acts on the tissues it must be converted to dihydrotestosterone. Present also in women, being converted from the weaker androgen androstenedione.