Nail clubbing

In medicine, clubbing is a deformity of the fingers and fingernails that is associated with a number of diseases, mostly of the heart and lungs. Idiopathic clubbing can also occur.

Clubbing is associated with lung cancer, interstitial lung disease, tuberculosis, cyanotic heart disease, Crohn's disease and ulcerative colitis.

Even though clubbing is a well established physical finding in many diseases, the physiological mechanism that actually causes clubbing is not well established. Current understanding is that these diseases cause vasodilation in the distal circulation which leads to hypertrophy of the tissue of the nailbeds and thus to the clubbed fingernails.