Dihydrotestosterone, DHT, is closely related to scalp hair loss in men who have inherited a genetic sensitivity to this by-product of testosterone, says WebMD. In these men, hair follicles on the scalp affected by DHT progressively grow thinner hair, and the hair lifespan is reduced until the follicle dies.
This condition is known as male pattern baldness, and hair can begin to thin at the crown of the scalp, at the hairline or in both areas simultaneously, according to WebMD. This eventually progresses until both thinning areas meet, leaving the men fully bald on the top of the scalp. The hair follicles in this area are the ones most sensitive to DHT in most men, although in some men, the pattern of baldness continues to progress to the lower half of the scalp.
The genetic progress of male pattern baldness is not fully known, but research has shown that DHT thins the hair growing from the affected follicles, reports WebMD. Suppressing the production of DHT in the body reverses the progressive thinning from these hair follicles. Researchers also know that the hair follicle must be exposed to DHT for a considerable amount of time before the hair follicle dies, so with medication, the process of hair loss from male pattern baldness can be greatly slowed or stopped completely in some men.