Male pattern baldness, or androgenetic alopecia, is the most common type of hair loss among males. As the name suggests, androgens (male sex hormones) and genetics play key role in this type of baldness.
Hormonal factor, especially a male sex hormone known as dihydrotestosterone (DHT), plays the most important role in baldness. DHT is a byproduct of testosterone so, many men consider it’s logical to assume that “If DHT comes from Testosterone, then more Testosterone means more DHT and more hair loss. So, if I’m going bald, i must be making too much testosterone.”
That is not the case for majority of balding men.
Can High DHT Cause Hair Loss?
Yes, it can. However, it is not the whole truth. While excessive DHT in the body, for example in body builders who abuse anabolic steroids, can cause hair loss; every balding man does not have high levels of DHT in blood. In fact, while the testosterone levels fall with age, our chances of baldness increases. Although a clear correlation of DHT with receding hair lines exists, we still do not know exact mechanisms of how this happens.
For reasons that are not well understood, DHT is essential for hair growth in beard, armpit or pubic region, but it is detrimental to head hair growth. In the individuals who experience baldness, very high levels of local (scalp tissue) DHT are found despite the serum (blood) DHT being normal. Abnormal levels of DHT near the hair roots is what causes hair loss.
DHT is attached to androgen receptors on hair follicles. Through an unknown mechanism, it then appears to trigger the receptors to begin miniaturizing, a process where hair root shrinks. Scientists believe that some people have a genetically transmitted susceptibility to otherwise normal levels of circulating androgens, particularly DHT. And that is why excess DHT concentrates in these areas (as evidenced by high scalp tissue DHT) while serum levels of DHT are maintained.
In the end, it largely comes to that little code in the genes, that causes over-expression of DHT receptors on hair follicles and presence of normal levels of androgens that result in Andro-Genetic baldness.