Fungal infection: onychomycosis
Serious disorders not to be missed
Iron deficiency: koilonychia
Liver disease: leuconychia
Endocarditis: splinter haemorrhages
Chronic kidney failure: white bands, half-and-half nail
Bowen disorder/squamous cell carcinoma
Atopic dermatitis (pitted nails)
Pyogenic granuloma (usually with ingrowing toenails)
Drug effects (e.g. tetracycline)
Connective tissue disorders (e.g. SLE)
Is the patient trying to tell me something?
Consider onychotillomania, where patients pick and self-mutilate their nails, resulting in parallel transverse grooves (washboard deformity or habit-tic nails).
Enquire about a history of severe stress or illness and possible onychotillomania, be it excessive nail biting, picking or cleaning. Ask whether the hands are frequently in wet work (e.g. dishwashing, soaps and detergents) or dirt.
Careful examination of nails: look for associated skin disease (e.g. psoriasis, atopic dermatitis, tinea pedis, lichen planus)
Clubbing is an abnormality of the fingertips rather than nails.
Crumbly white nails are not always caused by fungus.
Skin disorders that can involve nails include atopic dermatitis, psoriasis, epidermolysis bullosa, exfoliative dermatitis and lichen planus.