Injerto Capilar Dr. Rafael de Freitas experto en Trasplante Capilar
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HOME / Alopecia / Androgenetic Alopecia (AGA) or Common Baldness

Androgenetic Alopecia (AGA) or Common Baldness

Hair loss is closely related to genetics and androgen metabolism. It starts around 20-30 years old and develops a slow and progressive evolution.


It represents 90% of hair loss. It is the most frequent hair loss of both men and women. 


Genetic predisposition determines specific areas of the head. Also hormone DHT (Dihydrotestosterone) will play an important part. This hormone interacts as a specific androgenic receptor which leads to hair miniaturization of the upper region of the scalp, which causes baldness.

In order to stabilize baldness there exist some pharmacological treatments (they don´t stop progression but slow down the process). This treatment consists of the inhibition of 5 alpha-reductase enzyme, in which we can find 2 subtypes: Type I and II:

Type II is the responsible for converting testosterone into dihydrotestosterone.

Progressive hair miniaturization (sensitive androgenic hair follicle) on Frontal, side and back (crown) areas in men is called Male Androgenetic alopecia (MAGA) and in women Female Androgenetic Alopecia (FAGA).




Male baldness depends on genetic predisposition and androgens. Androgenetic influence is acquired by polygenic character inheritance from the mother, father or both of them. Genes containing baldness information are related to X chromosome.    


Follicles undergoing miniaturization experience pigmentation reduction, they become invisible, follicular cells die (follicular apoptosis) and the hair disappears. 


Male pattern hair loss is the recession of the frontal hair line and vertex baldness (crown). It is a progressive and slow progress which will end up with hair on back and both sides of the scalp.



Female pattern hair loss (FAGA) is also called androgenetic, since it has the same identity as male hair loss. However, androgen amount is fewer in women than in men and the hair loss distribution is also different.

Hair loss in women is due to hyperandrogenism with quick and gradual alopecia, which can be followed by other signs such as: rising androgen, hirsutism, amenorrhea and rising testosterone levels (which must be checked).

Female pattern hair loss is more diffuse compared to male baldness. In women, hair density is reduced in the frontal region and on the crown, but the frontal hair line is kept. 

In both men and women common baldness is defined by progressive decrease of the anagen phase length, rising of telogen phase duration and hair miniaturization of the scalp –which shows a common final via of the follicular regression. 

Diagnosing both men and women hair losses is based on a first glance patter examination.


Hair loss can be temporal or permanent. The trichologist doctor will diagnose the disorder and treat it according to the cause. 


Other factors that might be related to baldness can be:

  • Thyroid diseases
  • Stress
  • CSN diseases 
  • Medicine
  • Hormonal Alterations (Polycystic ovary syndrome)
  • Chemotherapy or radiotherapy treatments 
  • Surgery
  • Infectious diseases 
  • Nutritional shortage due to a lack of vitamins and minerals  
  • Ovarian cancer
  • Adrenal cancer
  • Post hysterectomy
  • Adrenarche 


When DHEA is high it is sometimes associated to prolactin, reduction of SHBG (Sex Hormone Binding Globuline), increase of 3-a-androstanediol glucoride.

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