Birth weight related blood concentrations of the neurotransmission amino acids glutamine plus glutamate, phenylalanine and tyrosine in full-term breastfed infants perinatally.

Background The amino acids glutamine plus glutamate, phenylalanine and tyrosine are implicated in neurotransmission. We aimed to evaluate these amino acid blood concentrations in full-term breastfed infants with different birth weight (BW) perinatally. Methods Breastfed full-term infants (n = 6000, males 3000, females 3000) BW 2000-4000 g were divided into four equal groups. Both males and females Groups A, 2000-2500 g, B 2500-3000 g, C 3000-3500 g, D 3500-4000 g. Blood samples on Guthrie cards, were taken on the 3rd day of life and quantified via a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Results Glutamine plus glutamate mean values were found to be statistically significantly different between males vs. females in all the studied groups. The highest values were determined in both males and females in group D. Statistically significantly higher values of phenylalanine appeared in group D vs. other groups. Tyrosine mean values were calculated to be statistically significantly different in both sexes in group A compared to other groups. Conclusions Differences of glutamine plus glutamate, phenylalanine and tyrosine levels among full-term newborns with different BW are presented for the first time in the literature. Newborns with BW 3000-4000 g are benefited by having higher concentrations of the mentioned neurotransmission related amino acids. Neonatal screening reference values for these amino acids in relation to BW could be established, not only for preterm and low BW infants but also for full-term newborns with BW >3000 g.