Muehrcke's lines

• these are transverse white lines which are related to changes in the nail bed (and thus don't grow out with the nail)
  • transverse white bands parallel to the lunula which usually occur in paired narrow white bands in the nail bed
  • bands will blanch with applied pressure (1)
• the cause seems to be oedema of the underlying connective tissue
• most commonly associated with hypoalbuminaemia (e.g. nephrotic syndrome) but may occur after trauma (2)
  • also reported to occur in patients with nephritic syndrome, glomerulonephritis, liver disease, malnutrition states, and after chemotherapy (1)

Reference:

1. Zaiac MN, Daniel CR. Nails in systemic disease Dermatologic Therapy 2002;15 (2); 99–106.
2. Arch of Dermatology 1989;125:133.