Paediatric CSF acylcarnitine reference ranges

Abstract

Acylcarnitines play a crucial role in energy metabolism pathways, primarily known for their involvement in the beta oxidation of fatty acids. However, their roles extend beyond mitochondrial transport; they also contribute to the synthesis of lipids in the brain. The alteration of both plasma and cerebrospinal fluid (CSF) acylcarnitine levels has been reported in various central nervous system (CNS) disorders. However, existing CSF acylcarnitine analysis has primarily focused on adults, highlighting a critical gap in paediatrics, and plasma may not fully reflect CNS-specific metabolic changes. This study aimed to establish reference ranges of CSF acylcarnitine concentrations in paediatric patients. Using LC-MS/MS, we profiled CSF acylcarnitines in 57 non-meningitis children. The acylcarnitine concentrations reported in this study range from 0.01 µM to 4.21 µM. These findings provide a critical reference for future research exploring the role of acylcarnitines in paediatric CNS disorders, bridging a significant gap in the current understanding of acylcarnitine metabolism in children.

Keywords: acylcarnitines; cerebrospinal fluid (CSF); children; paediatrics; reference ranges.

FIGURE 1

Coefficient of variance (CV; %) of each acylcarnitine calculated from the mean values of the pooled quality control samples across batches. C0-C12 had <20% CV (C0, C3, and C5 <10% CV), indicating low analytical variation. C14 had 31% CV, but this is because of the very low concentrations of this acylcarnitine.

FIGURE 2

Representative overlaid chromatograms of each acylcarnitine and its corresponding isotopically labelled internal standard. In each case, the analyte and its internal standard co-elute at identical retention times, producing overlapping peaks. This demonstrates correct assignment of the metabolite, confirms that the internal standard underwent the same chromatographic and ionisation conditions as the analyte, and ensures accurate and reliable absolute quantification.

FIGURE 3

Violin plots of the eight CSF acylcarnitines measured across the four age groups of ≤1 year old, >1 and ≤3 years old, >3 and ≤6 years old, and >6 and ≤12 years old (x-axis). Concentrations on the y-axis are reported as micromoles per L (µM). No major differences in acylcarnitines are observable across the four paediatric age groups.