hair loss in men
Male Pattern Hair Loss
In most men who experience balding, the cause is a condition referred to in the medical literature as Androgenetic Alopecia. This is the same type of hair loss that we commonly refer to as Male Pattern Baldness. Pattern hair loss is simply what the name implies, hair loss that occurs in a specific area or “pattern,” that is inherited from our parents.
The below modified Norwood classification illustrates typical patterns of hair loss in men. It is important to note that some patients may not resemble a specific classification
Andro refers to Androgens or male hormones. Male hormones are normally present to a greater degree in men and to a much lesser degree in women. The term genetic refers to the genetic or inherited nature of pattern balding. This is how it works. Every hair follicle has a genetic program inherited from both parents at conception (not the mother only) that controls this type of hair loss. At some point in time, because of this genetic program, certain follicles within the balding pattern become sensitive or vulnerable to the follicle killing effects of a very specific male hormone called dihydrotestosterone (DHT). Other follicles outside the pattern with a different genetic program remain insensitive or invulnerable to DHT.
So it’s not an excess of male hormones or the location of the follicle, but the follicle itself, and more specifically the genetic program affecting each follicle. These DHT sensitive follicles then begin to change, becoming progressively smaller, called miniaturization. The miniaturized follicles also have a shortened growth phase, so the hair strands become progressively shorter. If this process continues, uninterrupted, the hairs become extremely petite and lose pigment; the once large and long growing pigmented hairs are thus transformed into hair of similar quality to the tiny virtually invisible blonde hairs that grow on our face (vellus hair).
Hair Growth Cycle
Hair follicles normally exist in three phases of growth:
- A growth period called the Anagen phase, typically lasting three or four years, followed by
- A brief shriveling up period called the Catagen phase, followed by
- A dormant or resting period called the Telogen phase, usually lasting three or four months.
So, a normal hair follicle will typically grow for about three years and then rest for about three months, before regrowing a brand new hair strand. As the new hair grows and lengthens, it ejects the old hair strand resulting in the normal shedding of hair that we experience every day (we normally shed up to 50 or more hairs per day). This cycling will typically allow the hair shaft to grow about 18 to 24 inches (e.g. shoulder length hair) before it sheds. Some exceptional individuals have a naturally longer growth cycle and can, therefore, achieve much greater hair length (e.g. waist length hair).
Most of your follicles, approximately 90% to 95% (most people start out with about 100,000 hair follicles), are in the growth phase, growing approximately one half inch per month.
If your growth cycle is unusually short, the hair shaft won’t achieve much length. As mentioned, that’s one of the things that happens when the “Androgen sensitive” follicles within the pattern are continually exposed to normally present DHT.
Let’s recap and put it all together. Every hair follicle has a genetic code determined at conception. This genetic code controls “if” and “when” each follicle will become vulnerable to the hair killing effects of a normally present male hormone called dihydrotestosterone or DHT. When this happens, DHT begins to slowly diminish the now vulnerable follicles by:
- Causing Miniaturization, and
- Shortening the Anagen Phase
As a result, hair within the thinning or balding pattern becomes progressively finer, shorter, loses pigment, and sheds/cycles more frequently.