Androgenetic Alopecia -
pattern hair loss
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.
Androgenetic alopecia is the most common cause of hair thinning in both men and women. Hair thinning may begin any time after puberty when androgens are synthesized and manifest their presence by the reshaping of the frontal hairline from a straight hairline to an M-shaped hairline. Precise studies of prevalence of androgenetic alopecia in different population groups are not available. In the United States, about half of the men and women show some expression of this trait by the age of 40. In women, the presence of hair thinning is often unnoticed because of its milder presentation and the fact that women tend to mask the hair thinning with effective styling.
Symptoms of Androgenetic Alopecia
The hair loss seen with male pattern baldness usually starts on the top of the head, toward the back; on the sides; or near the front. After the hair falls out, there is no new regrowth. In many cases, the result is a receding hairline or bald spot. However, some men become completely bald.
Diagnosis of Androgenetic Alopecia
A careful history often suggests the underlying cause of alopecia. Crucial factors include the duration and pattern of hair loss, whether the hair is broken or shed at the roots, and whether shedding or thinning has increased. The patient's diet, medications, present and past medical conditions, and family history of alopecia are other important factors.
If the diagnosis is not clear based on the history and physical examination, selected laboratory tests and, occasionally, punch biopsy may be indicated.
Treatment of Androgenetic Alopecia
Treatment is either medical or surgical. The only proven medications that are indicated for AGA are topical minoxidil (Rogaine®) and oral finasteride (Propecia®). Minoxidil's success for cosmetically acceptable regrowth is approximately 10% in men. In women, 50% show minimal regrowth and 13% moderate regrowth. Treatment is lifelong. Seven percent of patients may experience some irritation (burning, itching, redness) from the minoxidil solution. The 5% minoxidil solution has greater efficacy than the 2% minoxidil solution (Rogaine®). Finasteride recently has been shown to have significant efficacy in male AGA. Finasteride reversed hair loss in 66% of men and stabilized hair loss in 83% of men after two years of follow-up. In women, the use of a systemic antiandrogen such as spironolactone (Aldactone®) 50 to 200 mg per day, cyproterone acetate (Androcur®), or flutamide (Eulexin®) may have some benefit in reducing the amount of hair thinning. Finasteride in not indicated in women.
Androgenetic Alopecia Research
Despite the recent research efforts aimed at elucidating the mechanisms behind hair loss in androgenetic alopecia, there is some way to go before a thorough understanding of this condition is achieved. Given that androgenetic alopecia is heritable, identification of the genes involved should lead to a thorough understanding of the causes of this condition.
Alopecia Universalis
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