High-dose amino acid infusion preserves diuresis and improves nitrogen balance in non-oliguric acute renal failure.

INTRODUCTION: The effects of protein-enriched diets on glomerular filtration have been described in normal subjects and in patients with chronic renal failure. In acute renal failure, the effects of administration of high rates of protein on renal function and nitrogen balance have not been studied in critically ill patients. The present study examines the effects of large doses of amino acids on the glomerular filtration rate and nitrogen balance in critically ill patients with acute renal failure.
METHODS: Fourteen critically ill patients with a creatinine clearance below 50 ml/min and conserved diuresis above 2,000 ml/day received 2000 non-protein kcal/day and either 75 g (Group 1) or 150 g (Group 2) of amino acids parenterally. Renal function tests, fluid balance, sodium and nitrogen balances, and furosemide administration were assessed on day 1 (baseline day when dextrose 5% was administered) and days 2, 3 and 4.
RESULTS: The two groups were comparable in terms of severity indices, sex and creatinine clearance. Group 2 was significantly older (p < 0.05). Blood urea nitrogen increased significantly in Group 1 but not in Group 2; creatinine clearance remained unchanged in the two groups. Group 2 patients had a significantly more positive cumulative nitrogen balance (-10.5 +/- 17 g/day vs. 9 +/- 8.3 g/day) (p < 0.01), less positive fluid balance (2003 +/- 1336 ml vs. -2407 +/- 1990 ml) and lower furosemide requirement (1003 +/- 288 mg vs. 649 +/- 293 mg) (p < 0.05).
CONCLUSION: A high amino acid regimen administered as a part of parenteral nutrition improves nitrogen balance, reduces furosemide requirements and ameliorates water balance in acute renal failure patients with conserved diuresis.