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Androgenic Alopecia

Androgenetic alopecia is an extremely common disorder affecting both men and women. The incidence is generally considered to be greater in males than females, although some evidence suggests that the apparent differences in incidence may be a reflection of different expression in males and females.

This genetically determined disorder is progressive through the gradual conversion of terminal hairs into indeterminate hairs and finally to vellus hairs. Patients have a reduction in the terminal-to-vellus hair ratio, normally at least 2:1. Following miniaturization of the follicles, fibrous tracts remain. Patients with this disorder usually have a typical distribution of hair loss.

Androgenetic alopecia is an extremely common disorder that affects roughly 50% of men and perhaps as many women older than 40 years. As many as 13% of pre-menopausal women reportedly have some evidence of androgenetic alopecia. However, the incidence increases greatly in women following menopause, and, according to one author, it may affect 75% of women older than 65 years.

The incidence and the severity of androgenetic alopecia tend to be highest in white men, second highest in Asians and African Americans, and lowest in Native Americans and Eskimos. Almost all patients have an onset prior to age 40 years, although many of the patients (both male and female) show evidence of the disorder by age 30 years.

History of Androgenic Alopecia:

  • The onset is gradual.
  • Men present with gradual thinning in the temporal areas, producing a reshaping of the anterior part of the hairline. For the most part, the evolution of baldness progresses according to the Norwood/Hamilton classification of frontal and vertex thinning.
  • Women usually present with diffuse thinning on the crown. Bitemporal recession does occur in women but usually to a lesser degree than in men. In general, women maintain a frontal hairline.

Causes of Androgenic Alopecia

Androgenetic alopecia is a genetically determined condition. Androgen is necessary for progression of the disorder, as it is not found in males castrated prior to puberty. The progression of the disorder is stopped if postpubertal males are castrated. Androgenetic alopecia is postulated to be a dominantly inherited disorder with variable penetrance and expression. However, it may be of polygenic inheritance. Recently, it was noted that follicles from balding areas of persons with androgenetic alopecia are able to produce terminal hairs when implanted into immuno-deficient mice. This suggests that systemic or external factors may play a role in this disorder.

Treatments for Androgenic Alopecia

  • Medical Care

Only 2 proven, food and drug administration (FDA)–approved medications are currently available for treatment of androgenetic alopecia: minoxidil and finasteride.

  • Minoxidil
  1. Although the method of action is essentially unknown, minoxidil appears to lengthen the duration of the anagen phase, and it may increase the blood supply to the follicle. Regrowth is more pronounced at the vertex than in the frontal areas and is not noted for at least 4 months.
  2. Patients who respond best to this drug are those who have a recent onset of androgenetic alopecia and small areas of hair loss. The drug is marketed as a 2% or a 5% solution, with the 5% solution being somewhat more effective. In general, women respond better to topical minoxidil than men.
  • Finasteride
  1. Finasteride i can be used only in men because it can produce ambiguous genitalia in a developing male fetus. It has been shown to diminish the progression of androgenetic alopecia in males who are treated, and, in many patients, it has stimulated new regrowth.
  2. Finasteride must be continued indefinitely because discontinuation results in gradual progression of the disorder. A study in postmenopausal women indicated no beneficial effect of the medication in treating female androgenetic alopecia.
  • Some drugs are non-FDA–approved but potentially helpful medications. In women with androgenetic alopecia, especially those with a component of hyperandrogenism, drugs that act as androgen suppressants or antagonists (eg, spironolactone, oral contraceptives) may be beneficial.
  • Androgenetic alopecia is very common; therefore, not surprisingly, it may accompany other forms of hair loss. Cases of telogen effluvium often occur in patients with underlying androgenetic alopecia. Therefore, a search for treatable causes of telogen effluvium (eg, anemia, hypothyroidism), especially in patients with an abrupt onset or a rapid progression of their disease, is indicated.
  • Surgical Care: Surgical treatment of androgenetic alopecia has been successfully performed for the past 4 decades. Although the cosmetic results are often satisfactory, the main problem is covering the bald area with donor plugs (or follicles) sufficient in number to be effective. Micrografting produces a more natural appearance than the old technique of transplanting plugs. Scalp reduction has been attempted to decrease the size of the scalp to be covered by transplanted hair.
  • Hair weaving techniques are available, and, together with hairpieces, they offer the patient a prosthetic method of coverage.