Persistent water diuresis in renal amyloidosis. A case report.

A 67-year-old male with previous history of osteomyelitis presented with persistent thirst and polyuria. His urine remained hyposmolar to plasma after overnight fasting and administration of pitressin. Biopsy and postmortem examination revealed renal amyloidosis with involvement of many glomeruli and smaller vessels. Amyloid was also found in the medulla, particularly around the collecting tubules. It is suggested that amyloid interfered directly with diffusion of water through the walls of the collecting tubules.