Alopecia (Hair Loss)



  • Absence of hair where it normally grows
  • Categorized as acquired or congenital
    • Most cases are acquired: Tinea capitis is most common, followed by traumatic alopecia and alopecia areata.
  • Also categorized as diffuse or localized
    • Most cases of alopecia are localized and, of these, tinea capitis is the most common.
  • Many normal healthy newborns lose their hair in the first few months of life.
    • Hair loss may be exacerbated by friction from bedding/sleep surface, especially in atopic infants.
  • Normally, about 50 to 100 hairs are shed and simultaneously replaced every day.
  • 90% of alopecia cases are due to the following disorders:
    • Tinea capitis
    • Alopecia areata
    • Traction alopecia
    • Telogen effluvium
      • Alopecia is preceded by a psychologically or physically stressful event 6 to 16 weeks prior to the onset of hair loss.
      • Growing hairs convert rapidly to resting hairs.

Risk Factors


  • Alopecia areata
    • Polygenic with variety of triggering factors
    • Family history in 10–42% of cases
    • Males and females equally affected
    • Onset usually before age 30 years
  • Monilethrix (also called beaded hair)
    • A rare autosomal dominant disorder

Commonly Associated Conditions

Trichotillomania is frequently associated with a finger-sucking habit.

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