alopecia areata

Last edited 10/2022 and last reviewed 10/2022

Alopecia areata

Alopecia areata is a relatively common condition which may occur at any age in either sex. The prevalence of Alopecia areata in the UK population is around 0.15%.

It is a non-scaring condition which can affect:

  • the hair follicles - damage is not permanent
  • the nails - 10-30% of patients
  • 40-50% of people develop their first hair loss before 21 years of age, and 20% of people after 40 years of age (1)
  • affects approximately 2% of the general population at some point during their lifetime (2)
  • most patients develop the condition before the age of 40 years with the with a mean age of onset between 25 and 36 years (2)
  • early-onset alopecia areata (mean age of onset between ages 5–10 years) predominantly presents as a more severe subtype, such as alopecia universalis (2)

Alopecia areata can be categorized according to extent or pattern of hair loss

  • Patchy - most common presentation with limited hair loss
  • Extensive - over 50% hair loss
  • Alopecia totalis - total loss of hair on the scalp
  • Alopecia universalis - total loss of body hair
  • Diffuse hair loss - can be seen occasionally

The cause is thought to be an autoimmune phenomenon as often; there is a co-existing autoimmune disease e.g. pernicious anaemia, thyroid disorders, vitiligo, diabetes.

There are lymphocytic infiltrates around the follicles, and a high prevalence of autoantibodies and abnormalities on the titres of circulating T lymphocytes (1).

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