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Alopecia androgenetica (AGA) or baldness comum

Hair loss is intimately related to genetics and androgenic metabolism. It usually appears to 20-30 year-olds with slow and progressive evolution.

It represents 90% of hair loss. It is the most frequent type of hair loss for both genders.

Genetic predisposition determines the specific areas of the head that will have a greater sensitivity to the DHT hormone (dihydrotestosterone).  This hormone interacts with a specific androgenic receptor leading to thee miniaturisation of the hairs of the upper region of the scalp, thus giving rise to baldness.

There are pharmacological treatments to stabilise baldness (it does not prevent progression, but it slows down the process). This treatment consists of the inhibition of an enzyme (5 alpha reductase, of which there are 2 subtypes: Type I and type II).

Type II is responsible for the conversion of testosterone to dihydrotestosterone.

The progressive miniaturisation of the hair (sensitive androgenic hair follicles) in areas of frontal, parietal and occipital (crown) androgenic influence in men is known as MAGA (Male Androgenic Alopecia).

This same progressive miniaturisation of the hair, but with a diffuse character and affectation, in women, is known as FAGA (Female Androgenic Alopecia).

Male Androgenic Alopecia | MAGA

Male baldness is undoubtedly a trait that depends on the amount of androgens and genetic predisposition.

Androgenic influence is acquired through the polygenic genetic code inherited from the father, the mother or both. Genes with baldness information and expression are related to the X chromosome.

The miniaturised follicles become fuzzy hair with decreased pigmentation (Fuzzy hair follicles), turning invisible after the death of follicular cells (follicular apoptosis) and disappearance of hair.

Hair loss in the male pattern is evidenced by the receding of the frontal hairline and in the baldness of the vertex (crown) in the scalp. It has a slow and progressive progress with a final result (baldness grade VII), in which there is hair just on the sides and back of the scalp.

Female Androgenic Alopecia | FAGA

Hair loss in the female pattern (FAGA) is also called androgenic, since it is considered to be the same entity that affects the male sex. The amount of androgen in females is lower than in males and the distribution of hair loss is also different.

In women, hair loss is a feature of hyperandrogenism with fast progressive alopecia, which is usually accompanied by other signs such as: androgen increase, hirsutism, amenorrhea and increased level of circulating testosterone, all of which should be examined.

Hair loss in the female pattern is a more diffuse process than male baldness, with a reduction in hair density in the crown at the frontal level, with preservation of the frontal hairline.

In both men and women, common baldness is characterised by a progressive decrease in the duration of the anagen phase and by an increase in the telogen phase with miniaturisation of the hair follicles on the scalp, evidencing a common end of follicular regression.

The diagnosis of both manifestations is based on the recognition of the male or female pattern at glance.

Hair loss can be temporary or permanent. The trichologist must diagnose the disorder and treat it in accordance with the cause. 

Other factors that may be related to baldness:

  • Thyroid diseases
  • Stress
  • CNS diseases
  • Medications
  • Hormonal changes (polycystic ovary syndrome)
  • Treatments with chemotherapy or radiotherapy
  • Surgery
  • Infectious diseases
  • Nutritional deficiency due to lack of vitamin and mineral intake.
  • Ovarian tumours.
  • Adrenal tumours.
  • Posthisterectomia.
  • Persistence of adrenarche

Although not always, DHEA is high, sometimes associated with prolactin, decreased SHBG (Sex Hormone Binding Globulin), increased 3-a-androstandiol glucoronide.