GPAtlas🧭 When to suspect
Alopecia areata is an autoimmune condition characterised by sudden, non-scarring hair loss. It typically presents as well-defined, smooth patches on the scalp or other hair-bearing areas. The condition can be highly unpredictable; while many patients experience spontaneous regrowth, others may progress to more extensive forms.
Suspect the diagnosis in any patient presenting with sudden patchy hair loss, particularly if the scalp appears otherwise normal with preserved follicular openings. Be aware of the distinct clinical variants:
| Variant | Presentation |
|---|---|
| Patchy alopecia areata | One or more well-demarcated coin-sized patches of hair loss; the most common presentation. |
| Alopecia totalis | Complete or near-complete loss of hair across the entire scalp. |
| Alopecia universalis | Complete loss of hair on the scalp and all body areas (including eyebrows, eyelashes, and body hair). |
| Ophiasis pattern | A band-like pattern of hair loss affecting the occipital and temporal margins; associated with a poorer prognosis. |
Severity is increasingly described using the Severity of Alopecia Tool (SALT), which scores the percentage of scalp hair loss: limited/mild (1–20%), moderate (21–49%), severe (50–94%) and very severe (95–100%). In practice the top two grades are combined into a single severe category (≥ 50% scalp loss, SALT ≥ 50) – the threshold at which specialist referral and systemic therapy become relevant.
A personal or family history of other autoimmune or atopic conditions – such as thyroid disease, vitiligo, type 1 diabetes, eczema, asthma, or hay fever – significantly increases the likelihood of the diagnosis. It is also more common in patients with Down's syndrome.
Source: DermNet · British Association of Dermatologists
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