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Age-specific distribution of plasma amino acid concentrations in a healthy pediatric population
N Lepage1, N McDonald, L Dallaire
1Département de Pédiatrie, Hôpital Sainte-Justine, Montréal, QC, Canada.
Insights
Reference values for 23 plasma amino acids were established in 148 healthy children. Quantile curves illustrate age-specific distributions, aiding in the diagnosis of amino acid metabolism disorders.
Area of Science:
- Biochemistry
- Pediatrics
- Clinical Chemistry
Background:
- Establishing reference ranges for plasma amino acids is crucial for diagnosing metabolic disorders.
- Previous studies have not comprehensively detailed age-specific amino acid concentrations across the pediatric population.
Purpose of the Study:
- To determine reference values for 23 plasma free amino acids in healthy children aged 0–18 years.
- To develop a novel graphical method for presenting age-specific amino acid distributions using quantile curves.
Main Methods:
- Plasma samples from 148 healthy children (0–18 years) were analyzed.
- Amino acid concentrations were measured using ion-exchange chromatography.
- Age-specific 10th, 50th, and 90th quantiles were calculated and plotted.
Main Results:
- Five distinct distribution profiles were identified among the 23 plasma amino acids.
- Nine amino acids initially decrease in the first year, then increase through adolescence.
- Nine amino acids show a continuous increase from infancy to adolescence.
Conclusions:
- Quantile curves provide a novel visualization of age-dependent amino acid variations.
- This graphical method can improve the monitoring of patients with inborn errors of amino acid metabolism.
Abstract:
Reference values were determined for 23 plasma free amino acids from measurements done in 148 healthy children ranging from 0 to 18 years of age. Amino acid analysis was performed by ion-exchange chromatography. We propose a graphic form of presenting the age-specific distribution of plasma amino acid concentrations where the 10th, 50th, and 90th quantiles are illustrated. Although each amino acid possesses its own pattern of distribution, we can identify five different profiles. Nine amino acids (alanine, arginine, asparagine, methionine, ornithine, phenylalanine, proline, threonine, and tyrosine) demonstrate a decrease in their concentrations during the first year of life; their concentrations then tend to increase throughout childhood and adolescence. Nine others (cystine, glutamine, glycine, histidine, isoleucine, leucine, lysine, tryptophan, and valine) show a steady increase throughout infancy, childhood, and adolescence. Five amino acids (aspartic acid, citrulline, glutamic acid, serine, and taurine) do not follow these two common profiles. For the first time, quantile curves are produced to illustrate the age-dependent variation of amino acid concentrations from infancy to adulthood. This alternative way of presenting amino acid concentrations may facilitate the follow-up of patients with inborn errors of amino acid metabolism.