Mannitol-Induced Diuresis: Its Effect on Serum and Urine Sodium Concentration

Introduction  In the past several years there has been renewed interest in the osmotic diuretic mannitol. In abdominal aortic aneurysmectomy mannitol has been widely used to maintain renal plasma flow and urinary output during cross-clamping of the abdominal aorta.¹ Increased urinary output during and after aortic surgery has been described in the literature^2,3 and confirmed by our own experience with the drug.Some discrepancies exist in published reports as to the amount of sodium lost in the urine during mannitol diuresis and the significance of this loss. In nonanesthetized, resting humans separate studies have shown that with mannitol diuresis there is increased sodium excretion with a significant decrease in serum sodium.^4,5 Boba, Gainor, and Powers⁶ have shown that anesthetized traumatized dogs infused with 10% mannitol undergo considerable urine sodium loss with marked decreases in serum sodium. Whelan,³ on the other hand, has reported that urine