There are multiple causes that produce the hair. A diet lacking in essential nutrients, thyroid problems, infections, stress, anemia, excessive cosmetics (dyes, flat iron), are factors which undoubtedly collaborate with alopecia. The side effects of some treatments may also cause fall hair. The chemotherapy or radiation are an example. However, Androgenic or Androgenetic Alopecia is the most common and involved in some way, to most men. 90% of men over 21 years has any recession frontotemporal area (inputs) and 50% of men over 40 years has the crown area depopulated. To be clear, 5 of 10 men (over 40 years) in both sectors suffer alopecia of the scalp and 9 out of 10 (greater than 21 years) suffer from alopecia only in the input (see left column).
Important:
Remember that it is quite normal to lose about a hundred hairs a day. The alopecia is diagnosed when new hairs are thinner than normal. Nor should we confuse a “fine hair” with alopecia as there are many people who have always had fine hair or looks weak. This does not necessarily mean alopecia. In androgenetic alopecia, those responsible for hair loss are the enzyme 5-alpha-reductase and the hormone testosterone. The enzyme converts testosterone into dihydrotestosterone (DHT), who ultimately is responsible for reducing the follicles, causing the scalp membranes to become rigid. In this way, the follicular structure receives less blood supply and new hairs are weaker and thin than normal. At the end of the process, follicles wither and hair that falls out is not replaced by new hair. We have studied the levels of DHT in patients with androgenetic alopecia usually normal. Therefore, science has determined that there is 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 just because they avoid the production of DHT.
Of testosterone to dihydrotestosterone (DHT)
The hair follicles receive testosterone (blue) and blood (red) blood vessels.
The enzyme 5-alpha reductase (5AR) converts testosterone into DHT (yellow).
DHT affects the normal hair growth
In men genetically predisposed to hair loss, when DHT levels rise following happens:
1. Shortens the growth phase (anagen).
2. The follicles become smaller, producing thinner hair.
3. The amount of visible hair is reduced.
