Clubbing is a thickening of the flesh under the toenails and fingernails. The nail curves downward, similar to the shape of the round part of an upside-down spoon.

Clubbing is associated with a wide number of diseases. It is most often noted in heart and lung diseases that cause a lower-than-normal amount of oxygen in the blood.

Clubbing may also be due to lung cancer, and diseases of the liver and gastrointestinal tract.

Clubbing may also occur in families. In this case it may not be due to an underlying disease.

• Bronchiectasis
• Celiac disease
• Cirrhosis
• Congenital heart disease (cyanotic type)
  • Tetralogy of Fallot
  • Total anomalous venous return
  • Transposition of the great vessels
  • Tricuspid atresia
  • Truncus arteriosus
• Crohn's disease
• Cystic fibrosis
• Lung abscess
• Lung cancer
• Pulmonary fibrosis

There is no specific treatment for the clubbing itself. Home care depends on the diagnosis.

If you notice clubbing, call your health care provider.

A person with clubbing generally has other symptoms and signs that define a specific condition. Diagnosis of that condition is based on:

• Family history
• Medical history
• Physical exam that looks at the lungs and chest

Medical history questions may include:

• Do you have any breathing difficulty?
• Does it affect the fingers, toes, or both?
• Is it becoming more noticeable?
• Is the skin ever bluish colored?
• What other symptoms are also present?
• When did you first notice this?

The following tests may be done:

• Arterial blood gas
• Chest CT scan
• Chest x-ray
• Echocardiogram
• EKG
• Pulmonary function tests

Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed. St. Louis, Mo; WB Saunders; 2005:78-79.

Murray J, Nadel J. Textbook of Respiratory Medicine. 3rd ed. Philadelphia, Pa: WB Saunders; 2000:506. 

Spicknall KE. Clubbing: an update on diagnosis, differential diagnosis, pathophysiology, and clinical relevance. J Am Acad Dermatol. 2005; 52(6): 1020-8