Androgenetic thinning

Androgenetic alopecia has a characteristic pattern of hair loss; it begins with a slight recession at the front hairline and is followed by thinning on the crown of the head. This hair loss results from a complex chemical reaction when the enzyme 5-alpha-reductase converts the testosterone in the system into DHT or dihydrotestosterone. The hair follicles are genetically predisposed to be oversensitive to the DHT and become smaller and smaller with time, leading to the eventual hair loss.