|Systematic (IUPAC) name|
|Mol. mass||290.442 g/mol|
|(what is this?)|
Dihydrotestosterone (commonly abbreviated to DHT), or 5α-dihydrotestosterone (5α-DHT), also known as androstanolone (5α-androstan-17β-ol-3-one) as well as 17β-hydroxy-5α-androstan-3-one, is a sex steroid and androgen hormone. The enzyme 5α-reductase synthesizes DHT in the prostate, testes, hair follicles, and adrenal glands. This enzyme reduces the 4,5 double-bond of the hormone testosterone.
Effects on sexual development
In men, approximately 5% of testosterone undergoes 5α-reduction to form the more potent androgen, dihydrotestosterone. DHT has two to three times greater androgen receptor affinity than testosterone and has 15-30 times greater affinity than adrenal androgens. The dissociation rate of testosterone from the receptor is five-fold faster than DHT. During embryogenesis DHT has an essential role in the formation of the male external genitalia, while in the adult DHT acts as the primary androgen in the prostate and in hair follicles.
An example illustrating the significance of DHT for the development of secondary sex characteristics is congenital 5-α-reductase (5-AR) deficiency. This gene lesion can result in pseudohermaphroditism. This condition typically presents with underdeveloped male genitalia and prostate. These individuals are often raised as girls due to their lack of conspicuous male genitalia. In the onset of puberty, although their DHT levels remain very low, their testosterone levels elevate normally. Their musculature develops like that of other male adults. After puberty, men with this condition have a large deficiency of pubic and body hair, and no incidence of male pattern baldness.
Unlike other androgens such as testosterone, DHT cannot be converted by the enzyme aromatase to estradiol. Therefore, it is frequently used in research settings to distinguish between the effects of testosterone caused by binding to the androgen receptor and those caused by testosterone's conversion to estradiol and subsequent binding to estrogen receptors.
DHT is the primary contributing factor in male pattern baldness that results from hair follicle miniaturisation. However, female hair loss is more complex, and DHT is only one of several possible causes. Women with increased levels of DHT may develop certain androgynous male secondary sex characteristics, including a deepened voice and facial hair. DHT plays a role in the development and exacerbation of benign prostatic hyperplasia, as well as prostate cancer, by enlarging the prostate gland. Prostate growth and differentiation are highly dependent on sex steroid hormones, particularly DHT.
Benefits in chronic heart disease
DHT has beneficial effects on stable resting ischemia in patients with chronic heart disease. Chronic DHT administration in these patients significantly increases total exercise time, time to the onset of angina and time to 1 mm ST depression.
5α-reductase inhibitors are commonly used for the treatment of two DHT-related conditions, male pattern baldness (MPB), and benign prostatic hyperplasia (BPH). Dutasteride is approved for the treatment of benign prostatic hyperplasia, and is prescribed off-label for the treatment of male pattern baldness, whereas finasteride is approved for both conditions. Dutasteride is three times more potent than finasteride in inhibiting the type II enzyme and 100 times more potent than finasteride in inhibiting the type I form of the DHT-producing enzyme. Both finasteride and dutasteride are potent inhibitors of the third isotype of the enzyme.
However, 5α-reductase inhibitors are thought to have persistent side effects that can continue after quitting the treatment, including diminished libido, erectile dysfunction and male breast cancer, and are suspected to have persistent cognitive side effects, including depression, brain fog and memory loss.
- Hemat RAS (2004). Principles Of Orthomolecularism. Urotext. p. 426. ISBN 1-903737-05-2.
- Grino, P. B.; Griffin, J. E.; Wilson, J. D. (1990). "Testosterone at high concentrations interacts with the human androgen receptor similarly to dihydrotestosterone". Endocrinology 126 (2): 1165–1172. doi:10.1210/endo-126-2-1165. PMID 2298157.
- Amory JK, Anawalt BD, Matsumoto AM, Page ST, Bremner WJ, Wang C, Swerdloff RS, Clark RV (June 2008). "The effect of 5alpha-reductase inhibition with dutasteride and finasteride on bone mineral density, serum lipoproteins, hemoglobin, prostate specific antigen and sexual function in healthy young men". J. Urol. 179 (6): 2333–8. doi:10.1016/j.juro.2008.01.145. PMC 2684818. PMID 18423697.
- Marks LS (2004). "5α-reductase: history and clinical importance". Rev Urol. 6 Suppl 9: S11–21. PMC 1472916. PMID 16985920.
- Swerdloff RS, Wang C (October 1998). "Dihydrotestosterone: a rationale for its use as a non-aromatizable androgen replacement therapeutic agent". Baillieres Clin. Endocrinol. Metab. 12 (3): 501–6. PMID 10332569.
- Nordqvist C (2012-02-23). "What Is DHT (Dihydrotestosterone)? What Is DHT's Role In Baldness?". Medical News Today.
- "Male Pattern Baldness Causes". Hair Loss Health Center. WebMD, LLC.
- McAndrews PJ. "Women's Hair Loss / Causes of Hair Loss". American Hair Loss Association.
- "Prostate Enlargement - What Causes The Prostate To Enlarge?". ehealthMD.
- Freedland SJ, Isaacs WB, Platz EA, Terris MK, Aronson WJ, Amling CL, Presti JC, Kane CJ (October 2005). "Prostate size and risk of high-grade, advanced prostate cancer and biochemical progression after radical prostatectomy: a search database study". J. Clin. Oncol. 23 (30): 7546–54. doi:10.1200/JCO.2005.05.025. PMID 16234520.
- Palusiński R, Barud W, Biłan A, Witczak A, Myśliński W, Hanzlik J: [Effect of dihydrotestosterone treatment on exercise induced ischemia in men with stable ischemic heart disease]. 2000 Aug;9(50):533-4.
- Olsen EA, Hordinsky M, Whiting D, Stough D, Hobbs S, Ellis ML, Wilson T, Rittmaster RS (December 2006). "The importance of dual 5alpha-reductase inhibition in the treatment of male pattern hair loss: results of a randomized placebo-controlled study of dutasteride versus finasteride". J. Am. Acad. Dermatol. 55 (6): 1014–23. doi:10.1016/j.jaad.2006.05.007. PMID 17110217. Lay summary – IAHRS Hair Transplant & Hair Loss Info Center.
- Irwig MS, Kolukula S (June 2011). "Persistent sexual side effects of finasteride for male pattern hair loss". J Sex Med 8 (6): 1747–53. doi:10.1111/j.1743-6109.2011.02255.x. PMID 21418145.
- Traish AM, Hassani J, Guay AT, Zitzmann M, Hansen ML (March 2011). "Adverse side effects of 5α-reductase inhibitors therapy: persistent diminished libido and erectile dysfunction and depression in a subset of patients". J Sex Med 8 (3): 872–84. doi:10.1111/j.1743-6109.2010.02157.x. PMID 21176115.
- Rahimi-Ardabili B, Pourandarjani R, Habibollahi P, Mualeki A (2006). "Finasteride induced depression: a prospective study". BMC Clin Pharmacol 6: 7. doi:10.1186/1472-6904-6-7. PMC 1622749. PMID 17026771.
- Rizner TL, Lin HK, Peehl DM, Steckelbroeck S, Bauman DR, Penning TM (July 2003). "Human type 3 3alpha-hydroxysteroid dehydrogenase (aldo-keto reductase 1C2) and androgen metabolism in prostate cells". Endocrinology 144 (7): 2922–32. doi:10.1210/en.2002-0032. PMID 12810547.