Nail fragility syndrome and its treatment.

For reasons of clarity, definitions are offered for strength, hardness, flexibility, brittleness and toughness of the nails. Six clinical types of nail fragility are delineated: longitudinal furrows and splitting (onychorrhexis), single longitudinal splitting, multiple crenellated splitting, lamellar splitting (onychoschizia), transverse splitting and nail friability. Changes may be observed in the keratin structure of fragile nails. Nail brittleness is usually 'environmental' in origin, but sometimes may be part of a nail dystrophy. Household daily chores are particularly damaging. Among the acquired general causes, hypochromic anaemia and sideropaenia, arthritic deformities of the distal joints, peripheral vascular impairment and endocrinopathies are the best known. Useful therapeutic approaches are updated. They entail protection with plastic gloves worn over light cotton glove linings, the use of nail hardeners composed of two main types of products: a modified nail varnish that functions as a base coat or a hardener, such as dimethyl urea, which overcomes the objections related to formaldehyde; a systemic drug, biotine, is still useful.