The relationship between testosterone and hair loss is complicated. A popular belief is that bald men have high levels of testosterone, but is this really true?
Male pattern baldness, or androgenic alopecia, affects an estimated 50 million men and 30 million women in the United States, according to the National Institutes of Health (NIH). Hair loss is due to the shrinkage of hair follicles and the resulting impact on the growth cycle. 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 certain genes.
Testosterone exists in your body in different forms. There’s “free” testosterone that isn’t bound to proteins in your body. This is the form of testosterone 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 isn’t 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, skin, and hair follicles.
Male pattern baldness (MPB) has a distinctive shape. The front 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.
Dihydrotestosterone (DHT) is made from testosterone by an enzyme called 5-alpha reductase. It can also be made from DHEA, a hormone more common in women. DHT is found in skin, hair follicles, and 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 doesn’t develop normally. With too much DHT, a man can develop benign prostate hypertrophy, also known as an enlarged prostate.
There is some evidence of a link between baldness and prostate cancer and other diseases. Harvard Medical School reports that men with vertex baldness have 1.5 times more of a risk of developing prostate cancer than men without bald spots. The risk of coronary artery disease is 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 not the amount of testosterone or DHT that causes baldness; it’s the sensitivity of your hair follicles. That sensitivity is determined by genetics. The AR gene makes the receptor on hair follicles that interact 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 may also play a part.
Age, stress, and other factors can influence whether 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.
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 highly sensitive to testosterone or DHT.
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 doesn’t recede. Female pattern hair loss (FPHL) is also due to the actions of DHT on hair follicles.
Several methods of treating MPB and FPHL involve interfering with testosterone and DHT’s actions. Finasteride (Propecia) is a drug that inhibits the 5-alpha reductase enzyme that converts testosterone to DHT. It’s 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 5-alpha reductase inhibitor called dutasteride (Avodart) is currently being looked at as a potential treatment for MPB. It’s currently on the market for treatment of an enlarged prostate.
Other treatment options that don’t involve testosterone or DHT include: