There are multiple causes for the hair loss
A diet lacking esencial nutrients, thyroid problems, infections, stress, cosmetic excess, are factor that contribute to Alopecia.
The side-effects of some treatments can provoke hair loss.
Chemotherapy or radiations are an example of this.
Anyway, the Androgenetic or Androgenic Alopecia
is the most common and is affecting to most men.
90% of men older than 21 yours present some type of recession on the front of the head. 50% of men older than 40 have
the top of the head affected.
To be more clear, 5 of every 10 men (older than 40) suffers Alopecia in both sections of the scalp and 9 every 10 men (older than 21)
suffering Alopecia only at the front of the head. (see the pictures on the left)
Remember that it's absolutely normal to loss around 100 hairs a day. Alopecia appears when the new hair is thinner than normal.
A lot of people confuse "thin hair" with Alopecia. There are a lot of people that have thin hair and this does not mean that they
In androgenetic alopecia, the enzyme 5-alpha-reductase and the hormone testosterone are the responsible for the hair loss.
The enzyme converts testosterone into dihydrotestosterone (DHT), who ultimately is responsible for reducing the follicles
causing the membranes of the scalp becoming rigid.
Thus, follicular structure receives less blood supply and new hairs are weaker and thinner than normal.
At the end of the process, the follicles atrophy and hair that falls out is not replaced by new hair.
Studied of the levels of DHT in people with androgenetic alopecia shows a normal result. Therefore, science has determined that
is not a high level of DHT which causes hair loss but a particular sensitivity of the follicles against DHT.
Treatments that inhibit the enzyme 5-alpha-reductase have good results precisely because they prevent the production of DHT.
From testosterone to dihydrotestosterone (DHT)
The hair follicles receive testosterone (blue) and blood (red) from blood vessels.
The enzyme 5-alpha-reductase (5AR) converts testosterone into DHT (yellow).
The DHT affect to the normal hair growing
In men genetically predisposed to hair loss, when DHT levels rise the following happens:
1 - shortens the growth phase (anagen).
2 - The follicles become smaller, producing thinner hair.
3 - The number of visible hairs is reduced.