Hair loss. Common congenital and acquired causes.

Hair loss is a common problem likely to be encountered by a clinical practitioner. The most frequent causes of hair loss in pediatric patients include tinea capitis, alopecia areata, traction alopecia, and trichotillomania. In the adult population, causes to be considered are alopecia areata and hair loss associated with systemic disease and hormonal influence. The clinician must be able to separate the types and causes of hair loss into those that reflect primary dermatologic conditions and those that represent reaction to systemic disease.