Male pattern baldness and DHT

Manligt håravfall och DHT

Male pattern baldness, or androgenic alopecia, is the most common type of hair loss among men. Hormonal factors appear to play a role, and in particular a male sex hormone called dihydrotestosterone (DHT). Hair loss affects about half of all men over 50. DHT has also been linked to hair loss in women, but this article will focus on male pattern hair loss.

Can male hormones cause hair loss?

DHT is an androgen and helps give men their male characteristics. DHT is thought to cause the hair follicles to decrease in size, and this contributes to male pattern baldness. By age 50, over half of all men will experience hair loss due to DHT. Treatments that block DHT can help prevent hair loss.

What Male Sex Hormones Cause Thinning Hair?

DHT has many roles. In addition to hair production, it is linked to benign prostatic hyperplasia, or enlarged prostate, but also prostate cancer. DHT is produced in the gonads, and is an androgenic hormone.

Androgens are responsible for the biological characteristics of men, including a deeper voice, body hair and increased muscle mass. During fetal development, DHT plays an important role in the development of the penis and prostate gland.

In men, the enzyme 5-alpha-reductase (5-AR) converts testosterone to DHT in the testis and prostate. Up to 10% of testosterone is normally converted to DHT. DHT is more powerful than testosterone. It attaches to the same place as testosterone, but much lighter. Once there, it is bound no longer.

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What is male pattern baldness?

Androgenic alopecia (hair loss) is the most common type of hair loss in men. The hair at the temples and on the top of the head becomes thinner and thinner over time, and eventually disappears completely.

The exact reason why this happens is unknown, but genetic, hormonal and environmental factors are all believed to play a role. DHT is believed to be an important factor.

How does hair grow?

To understand male pattern baldness, one must understand how hair grows. Hair growth is divided into three phases: anagen, catagen and telogen phase:

In the Anagen phase, the hair shaft is formed, which pushes up towards the skin's surface and pushes out the old shaft. Approximately 85–90 percent of hairs are in the anagen phase. Then follows the catagen phase or resting phase, and finally the telogen phase, where the hair falls out while a new hair in the anagen phase shoots up from below.

Why does male pattern baldness occur?

Male pattern baldness occurs when the follicles slowly become smaller, the anagen phase becomes shorter and the telogen phase becomes longer. The shortened phase means that the hair cannot grow as long as before. Over time, the anagen phase becomes so short that the new hairs do not even peek out through the surface of the skin.

As the follicles shrink, the hair becomes thinner with each growth cycle. Eventually, the hair is reduced to vellus hair, the type of soft, light hair that covers an infant and mostly disappears during puberty, in response to androgens.

Those who use anabolic steroids, including bodybuilders, have higher levels of DHT. And these individuals often experience hair loss.

What happens to the hair when there are too many male hormones in the body?

The hair on the head grows without the presence of DHT, but the hair under the arms, pubic hair and beard cannot grow without androgens. Individuals who have been sterilized or those who are deficient in the enzyme 5-alpha reductase (5-AR) do not experience male pattern baldness, but they will also have very little hair elsewhere on the body. For reasons that are not yet well understood, DHT is important for hair growth in various parts of the body, but it is detrimental to hair growth on the head.

DHT is believed to attach to the androgen receptors on the hair follicles. Through an unknown mechanism, DHT then appears to trigger the receptors to begin to decrease in size.

In 1998, researchers found that both plucked follicles and skin from a balding scalp contain higher levels of androgen receptors than those from a non-balding scalp.

Some researchers believe that some people have a genetically transmitted susceptibility to otherwise normal levels of circulating androgens, particularly DHT. This combination of hormonal and genetic factors may explain why some people are more prone than others to losing their hair.

Why do some people lose more hair than others?

DHT affects people in different ways, and this can be due to:

  • an increase in DHT receptors at the hair follicle
  • a greater local DHT production
  • higher androgen receptor sensitivity
  • more DHT produced elsewhere in the body and arriving through circulation
  • more circulating testosterone that acts as a precursor to DHT

DHT is known to bind to follicle receptors five times more easily than testosterone, but the amount of DHT in the scalp is small compared to the levels in the prostate.

Can Too Much Testosterone Cause Hair Loss?

5-alpha reductase (5-AR) is the enzyme that converts testosterone to the much more potent androgen, DHT. If 5-AR levels increase, then more testosterone will be converted to DHT, resulting in increased hair loss.

There are two types of 5-AR: type 1 and type 2 enzymes.

  • Type 1 is mainly found in sebaceous glands that produce the skin's natural lubricant, sebum.
  • Type 2 is mostly found in the urogenital system (urinary tract and reproductive organs) and hair follicles.

Can you take medication for male pattern baldness?

Male pattern baldness can have a negative effect on a man's self-esteem. Finasteride, or Propecia, is often prescribed to those who lose a lot of hair. It is a selective inhibitor of type 2 5-AR. It is believed to act on the 5-AR enzyme that concentrates in the hair follicles, to inhibit the production of DHT. Research has shown that it can stop the development of baldness, and that in some cases hair will start to appear again.

Finasteride can be taken orally every day. However, if treatment is stopped, hair loss will continue.

What are the most common causes of hair loss in men?

Alcohol

Alcohol leaches the body of important vitamins and minerals that are important for, among other things, the hair, including the mineral zinc and various B vitamins.

Medication

Increased hair loss and thinning hair can also be caused by certain medications such as antidepressants, blood thinners and chemotherapy.

Dietary supplements

Overdosing on certain nutritional supplements can cause side effects such as increased hair loss and thinning hair; these include vitamin A, vitamin E, zinc and selenium.

Diseases

Certain diseases such as diabetes, Rheumatoid Arthritis (RA), thyroid diseases (hypothyroidism and hyperthyroidism), Alopecia areata, and infectious disease with fever, can cause hair loss and thinning hair.

Also certain diseases and conditions such as inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis, can cause hair loss. In this type of disease and condition, there is often a deficiency of iron, vitamin B12 and vitamin B9. Another example is gluten intolerance (celiac disease), where deficiencies in iron, vitamin B12 and vitamin B9 can be seen.

Diet (eg vegetarians and vegans)

A diet with too little protein can contribute to increased hair loss and thin hair. Even a diet with too little nutrition (vitamins and minerals) contributes to increased hair loss and thin hair.

Weight loss

Hair loss after severe weight loss is usually associated with a condition known as telogen hair loss (effluvium). Severe weight loss causes physical stress, which signals the hair follicles to enter an inactive stage, where hair production shuts down and the hair follicles are put into a resting phase. Here, a lot of hair is lost in the telogen phase in a short time, perhaps 1000 hairs daily, for one or a few weeks. Usually the hair loss comes 2-3 months after the trigger.

Other causes of this "diffuse hair loss" in men can be; infectious disease with fever, stress, various medical conditions and also chronic diseases such as rheumatoid arthritis and diabetes, as well as various medications.

Heredity and androgenic disposition

Androgenic hair loss - male hair loss, occurs due to increased sensitivity to testosterone of the hair follicle which eventually regresses (goes into involution). The condition affects genetically predisposed men and can start already after puberty at the age of 17–18. Usually manifests in middle age in more than half of all men.

Aging

As part of general aging, the number of active hair follicles decreases, around 20-30 percent, which causes the hair to become thinner and the hairline to become higher. This affects both men and women. Can also start early in adulthood (presenile).

Smoking

Cigarette smoke contains toxic chemicals that cause constriction of the blood vessels and block blood circulation in the hair follicles. Since the hair follicles then do not receive the necessary nutrients from the blood, the hair growth cycle is disrupted, which in turn leads to noticeable hair loss and thinning hair.

Stress

Different types of stress (physical and mental) can cause reactions in the body that lead to telogen hair loss. Stress can put the hair follicles into a "resting" phase so they don't produce new hair. Over time, hair can fall out, even if you just wash, comb or touch it. Telogen hair loss (effluvium) - can also be caused by the body not getting enough nutrition or by changes in hormone levels.