Baldness

The most common form of baldness seen is male pattern baldness, in which the hair recedes from the front of the head, and a bald patch develops on top. The trigger for this type of baldness, which is also known as androgenetic alopecia, is currently believed to be an enzyme, 5-alpha reductase, that converts the hormone testosterone into dihydrotestosterone[?] (DHT), which inhibits hair growth. The age at which the enzyme appears, if it does at all, is genetically determined.

Female pattern baldness, in which hair-loss is distributed evenly instead of forming a bald patch or a receding hairline, is less common. It is believed to result from a decrease in estrogen, a hormone that normally counteracts the balding effect of testosterone, which normally occurs in women's blood.

Hair loss is a frequent side-effect of chemotherapy.

Some mycotic infections can cause massive hair loss.

Other forms of baldness:

• Alopecia areata