Hair loss in Men
The most common cause of hair loss in men is genetic hair loss (sometimes known as androgenetic alopecia). Genetic hair loss in men may start in the 20s, 30s or 40s. By age 30, about 30 % of men have genetic hair loss and by age 50, about one-half of all men have genetic hair loss.
A large proportion of men develop hair loss according to the Hamilton Norwood scale :
Genetic factors play an important role in the tendency or predisposition for a man to develop hair loss. There are likely many genes involved. Hair loss can be inherited from both the father as well as the mother.
There is a lot of evidence that androgens contribute to male pattern balding. Some of the earliest evidence showed that castrated men with low testosterone did not develop male pattern balding. However, once androgen hormone therapy was given, many of these castrated men developed male pattern balding.
Another important clue came from studying a specific kindred of individuals living in the Dominican Republic. Some of these men lacked an enzyme known as 5 alpha reductase type 2, which is a key enzyme to convert testosterone to the very potent androgen called "DHT" or dihydrotestosterone. Men who lacked the enzyme 5 alpha reductase type 2 did not develop male pattern baldness. Some of the medications used to treat male pattern baldness nowadays inhibit the enzyme 5 alpha reductase type 2.
FDA approved treatments for genetic hair loss include topical 5% minoxidil and oral finasteride. Hair transplant surgery is also an effective means of restoring hair in men.