• Lung conditions (bronchogenic carcinoma; fibrosing alveolitis; mesothelioma; suppurative lung disease such as bronchiectasis, lung abscess and empyema)

• Cardiac conditions (infective endocarditis, cyanotic heart disease)

• GI tract conditions (cirrhosis, ulcerative colitis, Crohn’s disease)

• Thyroid disease (thyroid acropachy)

• Family history (hereditary clubbing).

• Increased curvature of the nails, obliteration of the angle of the nail. A positive Schamroth test is the absence of the normal diamond-shaped window created when the dorsal surfaces of the terminal phalanges of similar fingers are opposed (Fig. 218.1). (When in doubt, approximate the dorsal aspects of terminal phalanges of the fingers of both hands flexed at the interphalangeal joints. Normally, the angle between the nails does not extend more than halfway up the nail bed. In clubbing there is a wide and deep angle, Schamroth’s sign.)

• Loss of Lovibond’s angle (Fig. 218.2)

• The nails may have a drumstick appearance (see Fig. 106.1).

• Look for the following signs: