Male pattern hair loss, or androgenetic alopecia, is the most common type of hair loss among males. The male sex hormone dihydrotestosterone (DHT) may play a key role in hair loss.
Hair loss affects around half of all men over the age of 50 years, and around 50 million men in the United States (U.S.).
DHT has also been linked to hair loss in women, but this article will focus on male pattern baldness.
Fast facts on dihydrotestosterone
DHT is an androgen and helps give males their male characteristics.
DHT is thought to cause hair follicles to miniaturize, and this contributes to male pattern hair loss.
By the age of 50 years, over half of the men in the U.S. will probably experience hair loss mediated by DHT.
Treatments that block DHT may help prevent hair loss.
What is DHT?
Male pattern baldness
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Male pattern baldness affects around half of men aged over 50 years in the U.S.
DHT has many roles. Apart from hair production, it is linked to benign prostatic hyperplasia, or enlarged prostate, and prostate cancer too.
DHT is a sex steroid, meaning it is produced in the gonads. It is also an androgen hormone.
Androgens are responsible for the biological characteristics of males, including a deeper voice, body hair, and increased muscle mass. During fetal development, DHT plays a vital role in the development of the penis and prostate gland.
In men, the enzyme 5-alpha-reductase (5-AR) converts testosterone into DHT in the testes and the prostate. Up to 10 percent of testosterone is normally converted into DHT.
DHT is more powerful than testosterone. It attaches to the same sites as testosterone, but more easily. Once there, it remains bound for longer.
Hair growth and hair loss
Male pattern hair loss is the most common type of hair loss in men. Hair at the temples and on the crown slowly thin and eventually disappear.
The exact reason why this happens is unknown, but genetic, hormonal, and environmental factors are all thought to play a role. DHT is believed to be a major factor.
Three phases of hair growth
To understand male pattern hair loss, we need to understand hair growth.
Hair growth is split into three phases: anagen, catagen, and telogen:
Anagen is the growth phase. Hairs remain in this phase for 2 to 6 years. The longer it lasts, the longer the hair grows. Normally, around 80 to 85 percent percent of the hairs on the head are in this phase.
Catagen lasts only 2 weeks. It allows the hair follicle to renew itself.
Telogen is the resting phase. The follicle lies dormant for 1 to 4 months. Normally between 12 and 20 percent of hairs are in this phase.
29 мар 2023
