Large volumes of urine in the early postoperative course of renal transplant patients:

A. Result from osmotic stimuli to diuresis.

B. May signify reversible polyuric acute tubular necrosis.

C. Should be replaced by administration of equal volumes of crystalloid.

D. Facilitate the diagnosis of rejection and obstruction of the renal artery and/or collecting system.

DISCUSSION: Factors responsible for the brisk diuresis following renal transplantation include osmotic stimuli secondary to high urea and/or glucose concentrations in the serum, and mild proximal tubular damage resulting from allograft ischemia. To avoid severe dehydration in the early postoperative period, an attempt should be made to replace urine losses with equal volumes of 0.45% NaCl solution to which 20 to 30 mEq. NaHCO 3 per liter may be added. The diagnosis of rejection and/or obstruction to urine flow is made easier when a transplanted kidney is undergoing voluminous diuresis rather than demonstrating oliguria or anuria secondary to severe acute tubular necrosis.