Clubbing of Nails

Normally a nail forms an angle of 130-160 degree, when looked from the side of the nail. When there is loss of normal angle between the nail surface and the skin covering the nail bed, it is called as clubbing of nail. It is more common in young males.

In normal nails, a diamond-shaped window appears at the nail beds when dorsums of two fingers from opposite hands are brought together. However, in clubbed nails, there is hypertrophy of the soft tissue below the nail bed. This makes the nail to bulge upwards, thereby distorting the growth of the nail and ultimately the nail gets curved. In such condition, the angle becomes greater than 160 degree. Even the terminal phalanx enlarges to make the finger appear bulbous.

The clubbing of nails may be unilateral or bilateral or may involve only a single digit. The exact phenomenon behind the occurrence of clubbed nails is still unknown.

Studies suggest that there is increased blood flow in the digits leading to vasodilatation and oedema that ultimately causes clubbing. Even hypoxia is also treated as a cause for increased blood flow to the digits, in certain heart and pulmonary disorders.

Clubbing of nails may be primary or secondary. Primary clubbing of nails occurs without any underlying medical cause (idiopathic). It may even be acquired genetically.

Secondary condition may develop in various disorders such as hypertrophy of the tissue below the nail, cancer of lungs, alveolitis of lung, asbestosis, inflammatory bowel disorder (crohn’s disease, ulcerative colitis), thyrotoxicosis, infective endocarditis, thyrotoxicosis, biliary cirrhosis etc. Some congenital disorders including congenital cyanotic heart disease, arterio-venous malformations etc may also be the reason.

On general physical examination, the normal diamond shaped window is not found and the nail also becomes spongy and moves freely in the nail bed. The whole digit (finger) appears like a drumstick.

Other diagnostic tests to exclude the underlying cause include medical history, clinical examination and x-ray.

Treatment aims at treating the underlying pathological condition.