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Clinical exam · Skin, head and neck

Digital clubbing and nail signs !

  • Sign

When fingertips swell and nails curve, a lung, heart or liver disease is usually behind it.

Updated 2026-11-01

See it in 3D: Distal phalanx, thumb · Distal phalanx, index finger · Distal phalanx, middle finger · Distal phalanx, ring finger · Distal phalanx, little finger

What it is

Clubbing is painless thickening of the soft tissue of the distal phalanx, with loss of the normal angle between the nail and the nail fold. It is a sign of chronic disease, mostly pulmonary (lung cancer, bronchiectasis, cystic fibrosis, pulmonary fibrosis), cyanotic heart disease, endocarditis and liver disease. The nails also show other useful bedside signs, such as koilonychia, splinter haemorrhages and pitting.

The anatomy it tests

  • Clubbing comes from connective tissue proliferation and increased blood supply between the nail matrix and the distal phalanx.
  • One accepted hypothesis: megakaryocytes and platelet clumps not filtered by the lung reach the fingertips and release growth factors.
  • It may come with hypertrophic osteoarthropathy: painful periostitis of long bones and arthritis, typical of lung cancer.

How to elicit it

  1. Look at the patient's hands at eye level, in profile, in good light; check the feet too.
  2. Profile angle: look at the angle between nail and nail fold; normally under 180°, in clubbing it flattens or exceeds 180°.
  3. Schamroth test: ask the patient to put the backs of the two index fingers together, nail against nail.
  4. Normally a small diamond-shaped window remains between the two nails; in clubbing the window disappears.
  5. Depth ratio: compare finger thickness at the nail bed with thickness at the distal interphalangeal joint; over 1 means clubbing.
  6. Press gently at the nail base: in clubbing the bed feels spongy, as if the nail were floating.
  7. Look for other nail signs: spoon shape, transverse grooves, pitting, bands, splinter haemorrhages and nail lifting.
  8. Ask how long the change has been present: hereditary clubbing is lifelong and has no associated disease.

What a positive result means

  • Most common cause: lung cancer; also bronchiectasis, cystic fibrosis, lung abscess, empyema and interstitial lung disease.
  • Cardiovascular: cyanotic congenital heart disease (such as tetralogy of Fallot) and infective endocarditis.
  • Digestive and other: cirrhosis, inflammatory bowel disease, coeliac disease and Graves disease (thyroid acropachy).
  • Uncomplicated COPD and asthma do not cause clubbing: if it appears in COPD, look for another cause, especially lung cancer.
  • Koilonychia (spoon nail): iron deficiency. Splinter haemorrhages: endocarditis (also trauma). Nail pitting: psoriasis.
  • Beau lines (transverse grooves): severe illness or chemotherapy months earlier. Onycholysis: psoriasis, hyperthyroidism, trauma. White proximal nails (Terry): cirrhosis.

Usefulness and limits

  • The Schamroth test is simple and useful at the bedside; measuring the profile angle and depth ratio is more objective.
  • Mild grades are hard to recognise and examiners disagree.
  • The finding is not a diagnosis: it prompts a search for the cause with history, chest exam and tests such as a chest X-ray.

Test yourself

Think of the answer, then tap the question to see it.

What is the Schamroth test and what does a positive result mean?

The backs of the index fingers are placed nail to nail; if the normal diamond window between them disappears, clubbing is present.

A patient with COPD develops clubbing. What should be suspected?

An added disease, especially lung cancer (or bronchiectasis), because uncomplicated COPD does not cause clubbing.

Which nail sign is linked to iron deficiency?

Koilonychia: thin, concave, spoon-shaped nails.

Which heart diseases are associated with clubbing?

Cyanotic congenital heart disease, such as tetralogy of Fallot, and infective endocarditis.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Clubbing of the fingers or toes: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2026); Nail abnormalities: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2026); Evaluation of the Patient With Pulmonary Issues - Pulmonology - Merck Manual Professional Edition (Merck Manuals, 2026).

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Representative model, for educational purposes only.