Clinical signs · Clinical photograph

Koilonychia (Spoon Nails)

Thin, concave nails that curve upward at the edges like a spoon — koilonychia, classically a sign of long-standing iron deficiency.

Fingernails that are thin and dished inward with raised edges, like the bowl of a spoon
Spooning of the nails (koilonychia).Image: CHeitz, via Wikimedia Commons — CC BY 2.0.

Written & reviewed by: Kinase Medical Team · Last reviewed: 30 September 2026 · Editorial policy

Key features

  • Thin, spoon-shaped (concave) nail plate.
  • A sign of advanced tissue iron deficiency, alongside cheilosis (fissures at the mouth corners).
  • Part of Plummer-Vinson syndrome: iron deficiency anaemia, oesophageal webs and dysphagia.
  • Other associations: diabetes, protein deficiency, connective tissue disease, solvent exposure, acitretin therapy.
  • Can be a normal finding in children.

Differential diagnosis

Differential diagnosis of Koilonychia (Spoon Nails)
ConditionHow to tell it apart
ClubbingIncreased (convex) nail curvature with loss of the nail-fold angle — the opposite shape.

How it appears in NEET PG

Nail images are a classic spot-diagnosis format; koilonychia is typically paired with a vignette of chronic blood loss or dysphagia (Plummer-Vinson).

Frequently asked questions

What deficiency causes koilonychia?

Iron deficiency is the classic cause; spoon nails indicate advanced tissue iron deficiency.

What is Plummer-Vinson syndrome?

The triad of iron deficiency anaemia, oesophageal webs and dysphagia; koilonychia is a common accompanying sign.

Is koilonychia ever normal?

Yes. Thin, spoon-shaped nails can occur in otherwise normal children.

Sources

  1. DermNet — Nail terminology
  2. Harrison's Principles of Internal Medicine (textbook)
  3. First Aid for the USMLE Step 1 (review text)

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For exam preparation and medical education only — not a substitute for clinical judgement, diagnosis or treatment of any patient.