Dynamic changes in blood amino acid concentrations in preterm infants in different nutritional periods.

<bold>Background and Objectives: </bold>Neonatal nutrition is critical for the growth and development of preterm infants. Dynamic changes in the amino acid profiles in preterm infants of different gestational ages and in different nutritional periods were investigated.<bold>Methods and Study Design: </bold>Premature infants who received parenteral nutrition support after birth were enrolled and divided into four groups based on their gestational ages. Blood samples were collected as a dried blood spot before nutritional support, and in the total parenteral nutrition, partial parenteral nutrition, and total enteral nutrition periods. Amino acid concentrations were detected in the samples by liquid chromatography tandem mass spectrometry and compared between the different nutritional periods and gestational ages.<bold>Results: </bold>Samples from 124 premature infants were statistically analyzed. Concentrations of all amino acids, except glutamine, were statistically different at distinct nutritional periods. Threonine and aspartic acid concentrations gradually increased, while valine, methionine, phenylalanine, and glycine concentrations gradually decreased with the transition from TPN to TEN. At different gestational ages, significant differences were observed in the concentrations of seven amino acids only in the PPN period but not in the others.<bold>Conclusions: </bold>The concentrations of amino acids in preterm infants vary with nutritional period. [ABSTRACT FROM AUTHOR]