Brown nail-bed arcs and chronic renal disease.

A brown arc affecting the distal part of the fingernail-bed, just proximal to the point of separation of the nail from its bed, has been found in 12 out of 34 patients with chronic renal disease (35%) compared with an incidence of less than 2% in a series of unselected patients. It represents a distinctive form of pigmentation, possibly due to lipochromes. No decisive association could be found between the presence or absence of the pigmented nail arc and the level of impaired renal function. Nevertheless it seems that renal disease predisposes towards the development of brown nail arcs.