Hair Growth

Hair grows about an inch every couple of months.  Each hair grows for 2 to 7 years, remains at that length for a short period, and then falls out.  A new hair soon begins growing in its place.  At any one time, about 85% of the hair on your head is in the growing phase and 15% is not.

Each hair sits in a cavity in the skin called a follicle.  Baldness in men occurs when the follicle shrinks over time, resulting in shorter and finer hair.  The end result is a very small follicle with no hair inside.  Ordinarily, hair should grow back.  However, in men who are balding, the follicle fails to grow a new hair.  Even though the follicles are small, they remain alive, suggesting the possibility of new growth.

The hair growth and rest cycle occurs in three phases: anagen, catagen and telogen.  The anagen phase is the period of active growth.  At any time, about 85 to 91% of hairs are in this active, anagen phase.  Anagen may last from 2 to 7 years, but usually about 3 years on average.  The catagen phase is considered transitional, and the telogen phase is the dormant or resting phase.  When the hair enters the telogen stage, the hair is either pulled out during normal grooming, or is pushed out when the new hair shaft growth begins.

DHT

Dihydrotestosterone, DHT is the testosterone derivative that is the predominant cause of hair loss in men.

From puberty, testosterone levels in our bodies increase.  These are converted by the type I and type II 5-alpha reductase enzymes in our blood, which alter the molecular composition, to create DHT.  This new hormone is an essential and powerful androgen, which causes male characteristics such as sexual organ development and function, body and facial hair growth and deepening of the voice.  When in contact with our scalp hairs, DHT acts as an irritant causing the follicles to weaken and their growth phases to progressively shorten, resulting in the hair thinning and eventual balding.