[Postobstructive polyuria in unilateral hydronephrosis. A case with 58 l/day]

Increased urinary outputs are common after release of bilateral ureteral or subvesical obstruction. However, polyuria is rare following unilateral obstruction. We report a case of excessive postobstructive diuresis of more than 58,000 ml per day (204 l in 10 days) after release of a left ureteral obstruction in a 56-year-old female, being the highest amounts reported in the literature. Polyuria was derived from the obstructed as well as from the normal contralateral kidney. The involved pathomechanism is complex and not completely understood. Treatment includes careful monitoring of the patient and replacement of fluid and electrolytes. In our case complete recovery of kidney function was observed after several days.