[Post-obstructive polyuria. Pathophysiological analysis of a case].

The relief of the impediment to urinary flow is the treatment of acute kidney failure due to urinary tract obstruction. However, there is a risk of inducing massive polyuria, which can be self-limited or produce severe contraction of the intravascular volume with pre-renal acute kidney failure and alterations in the internal environment. Polyuria, urine output > 3 L/d or > 200 mL/min for more than 2 hours, can have multiple causes, and can be classified as osmotic, aqueous or mixed.