Effects of Two Different Doses of Amino Acid Supplementation on Growth and Blood Amino Acid Levels in Premature Neonates Admitted to the Neonatal Intensive Care Unit: A Randomized, Controlled Trial

Abstract

OBJECTIVES. The goal was to measure the effects of 2 distinct strategies for parenteral nutrition on neonatal growth and blood amino acid profiles. METHODS. In a multicenter trial (n = 11 sites), we randomly allocated premature (23–29 weeks and 6 days of gestation) neonates to 1 of 2 approaches to intravenous amino acid administration. In one group, amino acid supplementation was started at 1.0 g/kg per day and advanced by 0.5 g/kg per day to a maximum of 2.5 g/kg per day (2.5 g/kg per day group). The other group received amino acids starting at 1.5 g/kg per day and advancing by 1.0 g/kg per day to a maximum of 3.5 g/kg per day (3.5 g/kg per day group). Filter paper blood spots were obtained from each infant on the day of random assignment and on days 7 and 28 of age, to monitor blood amino acid levels. RESULTS. We enrolled 122 neonates (64 in the 3.5 g/kg per day group and 58 in the 2.5 g/kg per day group). There were no differences in demographic or baseline characteristics between the 2 treatment groups. There was no significant difference in growth by day 28 after birth (median weight gain: 12.9 and 11.4 g/kg per day for the 3.5 and 2.5 g/kg per day groups, respectively), and the incidences of secondary morbidities were similar in the 2 groups. On day 7, blood levels of several amino acids and the serum urea nitrogen level were higher in the 3.5 g/kg per day group, compared with the 2.5 g/kg per day group; none of the amino acid levels were lower. CONCLUSIONS. Higher doses of amino acid supplementation did not improve neonatal growth and were associated with increased blood amino acid and urea nitrogen levels.