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Dihydrotesterone (DHT) - A Major Factor Behind Mens Hair Loss

What is Dihydrotesterone?

Dihydrotestosterone (DHT) belongs to the class of compounds called androgens, also usually called androgenic hormones or testoids (5) It is a biologically active metabolite of the hormone testosterone, and is organized mainly in the prostate gland, testes, hair follicles, and adrenal glands by the enzyme 5a-reductase (5). Testosterone is a male hormone, that is converted into DHT or Dihydrotestosterone in several tissues of the body and the skin (3). The enzyme 5 alpha reductase converts testosterone into its more potent form of DHT; it is thought to be around 30 times more potent than testosterone (5).

What is the function of dihydrotesterone (DHT)?

DHT has many important functions in the body. It is the Dihydrotestosterone levels in the womb that determine whether or not the fetus will develop into a male or female, which makes it a pretty strong androgen (3). As highlighted above, DHT is responsible for the development of all of the male secondary sexual characteristics like the deepening of the vocal chords, male hair patterns on the body, hair on the face, oily skin (especially when you first start puberty, and finally, male sexual drive and function.

Even so, DHT can cause problems for some people; for example it plays a role in the development and exacerbation of benign prostatic hyperplasia, as well as prostate cancer, by enlarging the prostate gland in some adult males(6). Prostate growth and differentiation are very reliant on sex steroid hormones, especially DHT. In addition, studies have now proven that Dihydrotestosterone (DHT) is the main causative factor in male pattern baldness and is to blame for up to 95% of hair loss (3,4).

The Effects of DHT on Hair Loss

Both men and women are inclined to lose their hair as a result of several hormonal changes in the body. Hair loss in androgenetic alopecia occurs mainly due to the adjustment in the metabolism of androgen in the body (2,5). This condition (commonly called male or female pattern baldness), has only been partially understood in the last few decades. For many years, scientists thought that androgenetic alopecia was caused by the predominance of the male sex hormone, testosterone, which women also have in trace amounts under normal conditions (1). While testosterone is at the center of the balding process, DHT is believed to be the major culprit and is the main antagonist of the hair follicles on your head.

The enzyme Type II 5-alpha reductase, helps convert testosterone into DHT, which is held in a hair follicle's oil glands (5;6). Scientists currently accept that it's not the quantity of circulating testosterone that's the problem, but the level of DHT binding to receptors in scalp follicles. DHT shrinks hair follicles, making it impossible for healthy hair to survive (5).

The follicles begin to produce less hair when they are genetically programmed to receiving DHT over a prolonged period of time. An increased level of DHT in the scalp causes the growth phase of hair to be shortened. However this is only the first step of hair loss. From there onwards hair becomes more brittle and begins to thin. It begins to fall out at a much quicker rate then it should and people tend to begin to experience a reduced hair line, thinning, and even baldness. In male pattern baldness, each consecutive growing/shedding cycle results in the production of finer and finer (less thick) hairs by the affected follicles, until the hair is unable to break the surface of the skin. (5) Hence, once DHT binds to large numbers of receptors of the hair follicles in the scalp, the follicles gradually shut down and eventually become dormant (6).

picture showing dihydrotes-tosterone (dht) effects on identical twins hair loss Above you can see the difference in hair count between me (right) and my twin brother (left). My twin has been using Dutasteride since late 2004 to block DHT from forming in his scalp. I only started using it in January 2010 - more photos.

Both men and women experience the hormonal process of testosterone converting to DHT, which then harms hair follicles. Although, women have a tiny amount of the level of testosterone that men have in general, even a lower level can cause DHT- triggered hair loss in women (1). And surely when those levels rise, DHT is even more of a problem. Those levels can increase and still be considered as "normal" on a blood test, even though they are high enough to cause a problem. The levels may not rise at all and still be a problem if someone has the kind of body chemistry that is overly sensitive to even its regular levels of chemicals, including hormones(1).

Hormones function in the healthiest manner when they are in a delicate balance, therefore, androgens do not need to be increased to initiate a problem. Their opposite female hormones, when down, gives an edge to these androgens, such as DHT (1). Such an imbalance can cause hair loss (5;6)

Hormones are cyclical. Testosterone levels drop by 10 percent each decade in some men after age thirty. Women's hormone levels decrease as menopause approaches and drop sharply during menopause and beyond (1). The cyclic nature of both our hair and hormones is one reason hair loss can increase in the short term even when you are experiencing a long-term slowdown of hair loss while on a treatment that controls hair loss.

Can DHT creation be stopped?

There are two well known drugs that have been shown to block the conversion of testosterone into dihydrotesterone, they are Dutasteride and Finasteride. Read more about DHT blockers here.

References

  1. American Hair Loss Association | Women's Hair Loss / Causes of Hair Loss
  2. Bingham KD, Shaw DA. - The metabolism of testosterone by human male scalp skin. J Endocrinol. 1973 Apr;57(1):111-121.
  3. HAMILTON JB. - Patterned loss of hair in man; types and incidence. Ann N Y Acad Sci. 1951 Mar;53(3):708-728.
  4. Jenkins JS, Ash S. - The metabolism of testosterone by human skin in disorders of hair growth. J Endocrinol. 1973 Nov;59(2):345-351.
  5. Naito A, Sato T, Matsumoto T, Takeyama K, Yoshino T, Kato S, Ohdera M. Br J Dermatol 2008; 159 (2) - Dihydrotestosterone inhibits murine hairgrowth via the androgen receptor. Epublic med Jun 28
  6. Walsh PC, Hutchins GM, Ewing LL. - Tissue content of dihydrotestosterone in human prostatic hyperplasis is not supranormal. J Clin Invest. 1983 Nov;72(5):1772-1777.