Amino Acid Levels of Preterm Infants on Parenteral and Enteral Nutrition: A Cross-Sectional Study

To assess the serum amino acid (AA) levels among preterm infants receiving parenteral and enteral nutrition.

This cross-sectional study included very preterm neonates (≤ 32 weeks) and healthy term breastfed neonates as reference group between December 2022 and June 2024. Parenteral nutrition (PN) was commenced on day 1 of life for preterm neonates delivered at ≤ 30 weeks gestation. Neonates delivered at 31-32 weeks gestation did not receive PN. Standard feed regimens were followed for enteral nutrition with "early" commencement of human milk fortifier (HMF). AA levels were estimated by liquid chromatography tandem mass spectrometry after at least one week of full enteral nutrition for 31-32 weeks group, or parenteral followed by full enteral nutrition for ≤ 30 weeks group. AA levels in preterm infants were considered inadequate if found to be below the lowest level of corresponding AA levels in healthy term breastfed babies.

A total of 84 preterm neonates delivered at ≤ 30 weeks gestation, 56 preemies at 31-32 weeks gestation, and 100 term neonates were studied. Compared to term neonates, preterm infants ≤ 30 weeks on PN and EN had inadequate levels of phenylalanine, methionine, histidine, valine, glycine, glutamine, arginine, alanine, glutamic acid, and aspartic acid. Deficiencies were noted in > 10% of this group for phenylalanine, methionine, histidine and glycine; in 5-10% for valine, leucine/isoleucine, glutamine, alanine, glutamic acid; and in < 5% for tyrosine, arginine, serine, and aspartic acid.

Despite use of parenteral and enteral nutrition protocols based on current science, preterm (≤ 30 weeks) infants had amino acid levels significantly lesser than in term healthy breastfed neonates.