The cause in over 90% of male hair loss cases is known and recognised as hair loss at the front, top and/or the crown or vertex of the male scalp. This area is susceptible to hair loss and is a the non-permanent area. However, the back and sides of the scalp, where hair usually grows for life, is known as the ‘permanent’ area and as such this is used to harvest hairs and re-distribute into the thinning areas. This is referred to as to 'donor area'.
Male pattern hair loss is brought on by the presence of Dihydro-testosterone thus causing hair to thin over time and fall, whereas is the so-called permanent area this does not occur. The number and location of these susceptible hairs is determined by inherited genetics from one or both parents.
Hair is lost because of a change in the lifecycle of the hair root caused by DHT. In simple terms, this cycle consists of a growing phase and a resting phase. Before hair loss sets in, the growing phase lasts up to seven years and the resting phase lasts three to four months. Genetic hair loss is a result of the life cycle phases going into reverse i.e. the growing phase becomes shorter and shorter and the resting phase longer. Eventually, the hair grows very little or not at all.