Alopecia is the general medical term for hair loss, and it has many different causes. Normal human hairs can be classified according to their phases of growth. Anagen is the growing stage of hair, while telogen is the sleeping stage of hair.
About 80 percent of the hairs in the human scalp are growing hairs and about 20 percent of them are sleeping hairs. It has been estimated that the scalp normally contains about 100,000 hairs. Therefore, the average number of hairs that can be lost in a day is about 100. Contrary to popular belief, neither shaving nor hormonal changes, such as menstruation, has any effect upon hair growth. Hair loss can be broken down into several different types, including alopecia areata (temporary hair loss in a coin-shaped patch), telogen effluvium (temporary hair loss secondary to a stressor on the system), and androgenetic alopecia (male-pattern hair loss).
For the purposes of our discussion, we will focus on male-pattern hair loss. It generally shows itself in the 20s or early 30s by gradual loss of hair, chiefly on the top of the head and in the angles at the frontal hairline. There are several different patterns to this hair loss, but male-pattern hair loss is the most frequently encountered type. The exact mechanisms are still unknown. We have no doubt, however, that inherited factors and the effect of androgens (male hormones) on the hair are most responsible.
