Dihydrotestosterone (commonly abbreviated to DHT), or 5a-dihydrotestosterone (5a-DHT), also known as 5a-androstan-17ß-ol-3-one, is a sex steroid and androgen hormone. The enzyme 5a-reductase synthesizes DHT from testosterone in the prostate, testes, hair follicles, and adrenal glands. This enzyme reduces the 4,5 double-bond of the testosterone. Relative to testosterone, DHT is much more potent as an agonist of the androgen receptor.