EFFECT OF AMINO-ACID COMPOSITION OF PARENTERAL SOLUTIONS ON NITROGEN-RETENTION AND METABOLIC RESPONSE IN VERY-LOW-BIRTH WEIGHT INFANTS

To evaluate the influence of amino acid preparations on the metabolic response of parenterally fed immature newborn infants, N retention and plasma amino acid concentrations were compared in very low-birth-weight infants given 2 parenteral regimens, which differed only by the composition of the infused amino acids (Travasol 10% blend B and Vamin 7%). The intakes of fluid, N and calories were comparable. The N retention was 72% .+-. 7% with Vamin, and 65% .+-. 6% with Travasol. The differences in plasma amino acid concentrations were consistent with the composition of the amino acid solutions. During the infusion of Vamin, the increased intake of aromatic amino acids resulted in high plasma levels of tyrosine (256 .+-. 233 .mu.mol/L, range 67-894 .mu.mol/L). The infusion of Travasol resulted in high plasma levels of methionine (114 .+-. 39 .mu.mol/L, range 53-260 .mu.mol/L) and an elevated load of glycine, which was accompanied by an abnormally high urinary loss of this amino acid. Despite these metabolic imbalances, the growth rate over the whole study was adequate. The importance of the composition of amino acid solutions on the metabolic response of the very immature preterm infant was emphasized.