What is Male Pattern Hair Loss?
Male pattern hair loss, also known as androgenetic / androgenic alopecia affects all men to some degree as they age. Progressive thinning of the hair on the head eventually leads to baldness. The hair loss usually starts at the temples, with the hairline gradually receding. Subsequently, hair at the crown (back) of the head also starts to get thinner.
In serious cases, loss of hair advances over the entire crown of the head, leaving only a horseshoe pattern of hair around the back and sides of the head.
What causes male pattern hair loss?
The culprit is a hormone called dihydrotestosterone (DHT), which is converted from testosterone in the scalp. Over time, DHT develops around the hair follicle, causing the hair to thin, miniaturize and ultimately prevents the hair to grow. The follicle degenerates as a result, causing each new hair that cycles through the follicle to be gradually thinner than the previous one. Eventually the follicle shuts down altogether, stopping hair growth entirely and permanently.
Both a follicle’s resistance to DHT and the levels of DHT in the scalp are genetically determined, which explains why some people go bald and others do not. The gene can be inherited from both the mother and the father, so men with balding relatives (on either side of the family) have increased odds of losing their hair too.
In some families there are genes passed on through the family that make men more likely to have androgenetic alopecia. In men with these genes, the hair follicles are more sensitive to DHT. This leads to hair follicle miniaturization (where the hairs growing from the follicles become thinner and shorter with each cycle of growth) at a younger age.
The balding process is gradual and only hair on the scalp is affected.
What Male Pattern Baldness Looks Like
Male Pattern Baldness normally begins at the hairline. The hair follicles that are most sensitive to DHT are found at the temples, the hairline and on the crown of the head.
When Male Pattern Baldness is the cause of hair loss, the following signs are usually present:
- The hair line often recedes to form an “M” shape
- Hair at the crown of the head begins to recede
- Existing hair becomes finer and shorter
- The top of the hairline eventually meets the thinned crown, leaving a horseshoe pattern of hair around the sides of the head that continues to grow
The Norwood-Hamilton Scale
The most well-known measurement to classify the progression of Male Pattern Baldness is known as the Norwood-Hamilton Scale. This scale ranges from level I, which is little or no hair loss, to level VII—severe baldness with only a rim of hair remaining.
While the Norwood Scale is useful in generally categorizing male pattern hair loss, there are men who do not fall into one of these boxes or suffer from a different hair loss condition.