CAUSES OF CLUBBINGThere are various causes of clubbing. Clubbing was first described by Hippocrates. It is deformity of the nails mostly associated with cardiac and pulmonary conditions. Its basically the exaggeration of the normal nail curvature associated with the loss of normal angle between the nail and the posterior nail fold.

 

The sign demonstrated is known as the Schamroth Sign which is associated with clubbing. In this sign the normal diamond shaped window formed between opposing dorsal surfaces of the fingers is not present in clubbed fingers.

Causes of Clubbing 
One can remember the causes of finger clubbing by using the mnemonic CLUBBING.
C  Cyanotic heart disease
     Cystic fibrosis
     Crohns Disease
L   Lung cancer and abscess
      Lipoid Pneumonia
U Ulcerative colitis
B Bronchiectasis
   Benign mesothelioma
   Bronchogenic Carcinoma
   Biliary Cirrhosis
I Idiopathic pulmonary Fibrosis
  Infective endocarditis
N Neurogenic tumor
    Neoplasm of Lung Liver Esophagus Small and Large Bowel
G Gastrointestinal diseases ( cirrhosis and regional enteritis)
    Graves Disease

CAUSES OF CLUBBING
Stages of Clubbing
1. Increased nail bed fluctuation and ballotability
2. Loss of angle between nail bed and the cuticula which is normally <165° angle known as the Lovibond angle 
3. Increased convexity of nail fold / ungual bed
4.  Increased thickness of distal phalanx leading to a drum stick appearence.
5.  hypertrophic osteoarthropathy
Interesting associations of Clubbing
  • Unilateral clubbing occurs in pancoast tumor or aneurysms of subclavian, aorta and innominate artery.
  • Unidigital clubbing in which only a single digit is clubbed is related to digital mucoid cyst, osteomas, myxchondroma, trauma, gout and sarcoidosis.
  • Selective lower Limb clubbing also known as differential clubbing occurs in patients with patent ductus arteriosus associated with pulmonary hypertension and right to left shunt.
  • Differential clubbing is also associated with infected abdominal aortic aneurysm.
  • COPD and tuberculosis are not associated with clubbing.
  • If clubbing is present in association with these conditions (namely COPD and Tuberculosis) then underlying malignancy and bronchiectasis must be looked for.
  • Endocrine causes include myxedema, thyroid acropachy/ hyperthyroidism and acromegaly
  • Clubbing may also be idiopathic or hereditary
  • Chronic Bronchitis is not a cause of clubbing.