Plasma amino acid profiles by using ion-exchange chromatography in neonates from northeastern Thailand

Abstract

Background: The reference values for plasma amino acids in neonates are essential for making a diagnosis of inborn errors of metabolism (IEM). However, data on plasma amino acid reference ranges for northeastern Thai neonates remain limited.

Objectives: This study aims to establish reference intervals for plasma amino acids in healthy full-term neonates from northeastern Thailand.

Methods: Healthy full-term neonates from northeastern Thailand were enrolled. Two mL of heparinized blood was collected along with newborn screening blood spots during 48-72 hours of age. Plasma amino acids were analyzed using ion-exchange chromatography with post-column ninhydrin derivatization. Due to non-normal distribution, reference intervals were determined using the non-parametric percentile method, defined by the 2.5th and 97.5th percentiles. Results were compared with previous Thai studies.

Results: There were 42 full-term newborns (median gestational age: 38 weeks), of whom 22 were male (52.4%). Plasma amino acid levels were compared with those from previous Thai studies and other reference ranges. Some amino acid levels differed from previous studies, likely due to differences in analytical methods and age groups. Greater variability was observed in non-essential amino acids. When compared to other published reference values. The plasma amino acid profiles were specific to this population.

Conclusions: The reference ranges established in this study provide valuable data for the diagnosis and management of IEMs in Thai neonates. Differences from previous studies may reflect variations in measurement techniques and age groups. These findings emphasize the importance of region-specific reference data, particularly in populations with distinct demographic and environmental factors.