dihydrotestosterone dihydrotestosterone dihydrotestosterone (dht, 5α-dihydrotestosterone, 5α-dht, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. the enzyme 5α-reductase catalyzes the formation of dht from testosterone in certain tissues including the prostate gland, seminal vesicles, epididymides, skin, hair follicles, liver, and brain. this enzyme mediates reduction of the c4-5 double bond of testosterone. dht may also be synthesized from progesterone and 17α-hydroxyprogesterone via the androgen backdoor pathway in the absence of testosterone. relative to testosterone, dht is considerably more potent as an agonist of the androgen receptor (ar). this article is about dihydrotestosterone as a hormone. for its use as a medication, see androstanolone. dihydrotestosterone names iupac name 17β-hydroxy-5α-androstan-3-one systematic iupac name (1s,3as,3br,5as,9as,9bs,11as)-1-hydroxy-9a,11a-dimethylhexadecahydro-7h-cyclopentaphenanthren-7-one other names dht; 5α-dihydrotestosterone; 5α-dht; androstanolone; stanolone; 5α-androstan-17β-ol-3-one identifiers cas number 521-18-6 y 3d model (jsmol) interactive image chebi chebi:16330 y chembl chembl27769 n chemspider 10189 y drugbank db02901 y echa infocard 100.007.554 kegg c03917 y pubchem cid 10635 unii 08j2k08a3y y comptox dashboard (epa) dtxsid9022364 inchi inchi=1s/c19h30o2/c1-18-9-7-13(20)11-12(18)3-4-14-15-5-6-17(21)19(15,2)10-8-16(14)18/h12,14-17,21h,3-11h2,1-2h3/t12-,14-,15-,16-,17-,18-,19-/m0/s1 ykey: nvkawkqgwwiwpm-abevxsgrsa-n y smiles o=c4c3cc2(cc1(c)(o)cc12)3(c)cc4 properties chemical formula c19h30o2 molar mass 290.447 g·mol−1 pharmacology atc code a14aa01 (who) routes ofadministration transdermal (gel), in the cheek, under the tongue, intramuscular injection (as esters) pharmacokinetics: bioavailability oral: very low (due to extensive first pass metabolism) except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). y verify (what is yn ?) infobox references in addition to its role as a natural hormone, dht has been used as a medication, for instance in the treatment of low testosterone levels in men; for information on dht as a medication, see the androstanolone article. biological function dht is biologically important for sexual differentiation of the male genitalia during embryogenesis, maturation of the penis and scrotum at puberty, growth of facial, body, and pubic hair, and development and maintenance of the prostate gland and seminal vesicles. it is produced from the less potent testosterone by the enzyme 5α-reductase in select tissues, and is the primary androgen in the genitals, prostate gland, seminal vesicles, skin, and hair follicles. dht signals mainly in an intracrine and paracrine manner in the tissues in which it is produced, playing only a minor role, if any, as a circulating endocrine hormone. circulating levels of dht are one-tenth and one-twentieth those of testosterone in terms of total and free concentrations, respectively, whereas local dht levels may be up to 10 times those of testosterone in tissues with high 5α-reductase expression such as the prostate gland. in addition, unlike testosterone, dht is inactivated by 3α-hydroxysteroid dehydrogenase (3α-hsd) into the very weak androgen 3α-androstanediol in various tissues such as muscle, adipose, and liver among others, and in relation to this, dht has been reported to be a very poor anabolic agent when administered exogenously as a medication. selective biological functions of testosterone versus dht in male puberty testosteronedht spermatogenesis and fertilityprostate enlargement and prostate cancer risk male musculoskeletal developmentfacial, axillary, pubic, and body hair growth voice deepeningscalp temporal recession and pattern hair loss increased sebum production and acne increased sex drive and erections in addition to normal biological functions, dht also plays an important causative role in a number of androgen-dependent conditions including hair conditions like hirsutism (excessive facial/body hair growth) and pattern hair loss (androgenic alopecia or pattern baldness) and prostate diseases such as benign prostatic hyperplasia (bph) and prostate cancer. 5α-reductase inhibitors, which prevent dht synthesis, are effective in the prevention and treatment of these conditions. androgen deprivation is a therapeutic approach to prostate cancer that can be implemented by castration to eliminate gonadal testosterone as a precursor to dht, but metastatic tumors may then develop into castration-resistant prostate cancer (crpc). although castration results in 90-95% decrease of serum testosterone, dht in the prostate is only decreased by 50%, supporting the notion that the prostate expresses necessary enzymes (including 5α-reductase) to produce dht without testicular testosterone, that outline the importance of 5α-reductase inhibitors. dht may play a function in skeletal muscle amino acid transporter recruitment and function. metabolites of dht have been found to act as neurosteroids with their own ar-independent biological activity. 3α-androstanediol is a potent positive allosteric modulator of the gabaa receptor, while 3β-androstanediol is a potent and selective agonist of the estrogen receptor (er) subtype erβ. these metabolites may play important roles in the central effects of dht and by extension testosterone, including their antidepressant, anxiolytic, rewarding/hedonic, anti-stress, and pro-cognitive effects. 5α-reductase 2 deficiency