Retroperitoneal fibrosis presenting as spontaneously reversible renal failure.

Three patients are reported who presented with severe oliguric renal failure due to retroperitoneal fibrosis and obstructive uropathy in whom spontaneous diuresis and recovery of renal function took place, a course resembling acute tubular necrosis. There were, however, several clinical and laboratory findings that provided clues to the presence of obstructive uropathy. Two of the three patients had low back or abdominal pain. All three patients presented with anemia and significant hyperkalemic, hyperchloremic metabolic acidosis with only a small increase in anion gap and two of the patients had an inappropriately high urine pH. Neither tubular cell casts nor pigmented granular casts were identified in the urine in any of the patients. In all three patients the urine output increased from oliguric levels to 1400 - 2000 ml/day within 1 day associated with rapidly improving renal function. This report demonstrates and reinforces the need to rule out obstruction in all patients with renal failure of unknown etiology and adds retroperitoneal fibrosis to the list of diseases associated with renal failure and spontaneous recovery.