Hair Loss and Testosterone
The relationship between testosterone and hair loss is complicated. There’s the popular belief that bald men have high levels of testosterone, but is this really true?
Male pattern baldness or androgenic alopecia affects up to 70 percent of men and 40 percent of women in their lifetimes. Losing your hair involves the shrinkage of hair follicles. There’s less of a growth cycle as the follicles shrink. New hairs become finer and finer until there’s no hair left at all and the follicles become dormant. This hair loss is caused by hormones and the certain genes.
Different Forms of Testosterone
Testosterone exists in your body in different forms.
There’s “free” testosterone that is not bound to proteins in your body. This is the form of testosterone that is most available to act within the body.
Testosterone can also be bound to albumin, a protein in the blood. Most testosterone is bound to sex hormone-binding globulin (SHBG) protein and is not active. If you have a low level of SHBG, you may have a high level of free testosterone in your bloodstream.
Dihydrotestosterone (DHT) is made from testosterone by an enzyme. DHT is five times more potent than testosterone. DHT is primarily used by the body in the prostate, the skin, and in hair follicles.
Shape of Baldness
Male pattern baldness (MPB) has a distinctive shape. The frontal hairline recedes, especially at the sides, forming an M shape. This is frontal baldness. The crown of the head, also known as the vertex, becomes bald as well. Eventually the two areas join into a “U” shape. MPB can even extend to chest hair, which can thin as you age. Oddly enough, hair in different locations on the body can react differently to hormonal changes. For instance, facial hair growth can improve while other areas become bald.
Your hormone levels may affect your exact MPB symptoms. According to a study in the Journal of the American Academy of Dermatology, men with high levels of testosterone are more likely to have vertex baldness. The same study suggested that men with higher levels of the binding protein SHBG may have thinner hair on their chests.
DHT: The Hormone Behind Hair Loss
Dihydrotestosterone (DHT) is made from testosterone by an enzyme called 5a reductase. It can also be made from DHEA, a hormone more common in women. DHT is found in skin, hair follicles, and in the prostate. The actions of DHT and the sensitivity of hair follicles to DHT is what causes hair loss.
DHT also acts in the prostate. Without DHT, the prostate does not develop normally. With too much DHT, a man can develop benign prostate hypertrophy, also known as enlarged prostate.
DHT and Other Conditions
There is some evidence of a link between baldness and prostate cancer and other disease. Harvard Medical School reports that men with vertex baldness are at 1.5 times the risk of developing prostate cancer than men without bald spots. The risk of coronary artery disease was also more than 23 percent higher in men with vertex bald spots. Investigations are ongoing as to whether there is a link between DHT levels and metabolic syndrome, diabetes, and other health conditions.
It’s Your Genes
It’s not the amount of testosterone or DHT—it’s the sensitivity of your hair follicles. That sensitivity is determined by genetics. The AR gene makes the receptor on hair follicles that interacts with testosterone and DHT. If your receptors are particularly sensitive, they are more easily triggered by even small amounts of DHT, and hair loss occurs more easily as a result. Other genes likely also play a part.
Age, stress, and other factors can influence whether or not you experience hair loss. But genes play a significant role, and men who have close male relatives with MPB have a much higher risk of developing MPB themselves.
Myths – Virility and Hair Loss
There are a lot of myths out there about balding men. One of them is that men with MPB are more virile and have higher levels of testosterone. This isn’t necessarily the case. Men with MPB may actually have lower circulating levels of testosterone but higher levels of the enzyme that converts testosterone to DHT. Alternately, you may simply have genes that give you hair follicles that are very sensitive to testosterone or DHT.
A recent study in the Czech Republic showed that men with premature MPB actually had reduced levels of testosterone, SHBG, and other key hormones. The researchers concluded that MPB is similar to polycystic ovarian syndrome in women in terms of its hormone patterns.
Hair Loss in Women
Women may also experience hair loss due to androgenetic alopecia. Although women have much lower levels of testosterone than men do, there is enough to potentially cause androgenetic hair loss. Women experience a different pattern of hair loss. Thinning occurs over the top of the scalp in a “Christmas tree” pattern, but the front hairline does not recede. Female pattern hair loss (FPHL) is also due to the actions of DHT on hair follicles.
A review on hair loss in women in American Family Physician states that women with FPHL have higher levels of the enzyme 5a reductase, which is responsible for converting testosterone to DHT. They also tend to have sensitive receptors that react strongly to even small amounts of DHT. Most women with marked FPHL have normal levels of appropriate hormones—they just react more strongly to those hormones.
Treatments for Hair Loss
Several methods of treating MPB and FPHL involve interfering with the testosterone and DHT’s actions. Finasteride (Propecia) is a drug that inhibits the 5a reductase enzyme that converts testosterone to DHT. It is dangerous to use in women who may become pregnant, and there may be sexual side effects of this drug on both men and women.
Another 5a reductase inhibitor called dutasteride (Avodart) is currently being looked at as a potential treatment for MPB. It is currently on the market for treatment of enlarged prostate.
Other treatment options that do not involve testosterone or DHT include minoxidil (Rogaine), ketoconazole, laser treatment, and surgical hair follicle transplant.
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