Comparison of three low-nitrogen diets containing essential amino acids and their alpha analogues for severely uremic children.

Six infants, 4.5 to 19 months old, whose creatinine clearance was less than 6 ml/min/1.73 m2 received, successively, three low-nitrogen diets. Diet A contained 9.3 g of human milk protein; and diet B, 4.2 g of human milk protein plus synthetic essential amino acids. Diet C was the same as B except that five essential amino acids were replaced by alpha-keto and hydroxy analogs. Serum urea decreased as the infants were transferred from diet A to diets B and C, and the serum urea/creatinine ratio decreased from diet A to diet B and from diet B to diet C. Urea appearance was 14.8 +/- 4.5, 9.1 +/- 4.3, and 6.9 +/- 1.7 mmoles/day, with diets A, B, and C, respectively. Weight gain was also lowest with diet C, as was the difference between nitrogen intake and urea nitrogen appearance, an indicator of nitrogen balance. Plasma free amino acids were not modified by diets A and B, but valine, leucine, and the plasma free essential amino acid pool decreased significantly with diet C.