Dihydrotestosterone
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Dihydrotestosterone (DHT) is a biologically active metabolite of the hormone testosterone, formed primarily in the prostate gland, testes, hair follicles, and adrenal glands by the enzyme 5α-reductase by means of reducing the Δ4,5 double-bond. Dihydrotestosterone belongs to the class of compounds called androgens, also commonly called androgenic hormones or testoids. DHT is thought to be approximately 30 times more potent than testosterone.
Significance
DHT is produced by males in utero and is responsible for the formation of male gender specific characteristics. DHT is also an important contributor to other characteristics generally attributed to males, including muscular growth, facial and body hair growth, and deepening of the voice.
Pathology
It is suspected that DHT is the primary contributing factor in most cases of male-pattern baldness. Women with increased levels of DHT may develop certain androgynous characteristics typical of men, including hair above the lip, a deepened voice, and increased muscular growth. DHT also seems to play a role in the development or exacerbation of benign prostatic hyperplasia, or BPH, and prostate cancer, though the exact reason for this is not known.
Deficiency of, or insensitivity to, DHT in utero is a primary cause of physical gender ambiguity in males (see also: sexual differentiation, undervirilization, androgen insensitivity syndrome). Deficiency of DHT and other androgens such as testosterone in older men (also called andropause) can cause many sexual and non-sexual problems, and has been linked to an increased risk of development of alzheimer's disease.
Treatment
The class of drugs known as 5α-reductase inhibitors is used for treatment of problems stemming from overproduction of DHT, which includes finasteride (sold under the names Proscar for BPH and other problems and Propecia for androgenic alopecia) and dutasteride (sold under the name Avodart). Currently, DHT supplementation is not used as a treatment for DHT or androgen deficiency.
Alternative treatments used to inhibit DHT include dietary supplementation with, or topically administered preparations of, saw palmetto berry extracts, which appear to have some inhibitive effect on DHT production or effectiveness, though the method of its operation is not currently known. Also, the chemical equol, derived by consuming soy foods rich in soy isoflavones by persons with certain digestive-tract bacterial flora, appears to have an androgen-inhibitive effect; however persons without the necessary equol-producing bacterial flora will receive no benefit from that potential therapy.