Is it time to move beyond acylcarnitine profiles? Lessons from the clinical application of a high-definition LC-MS/MS acylcarnitine method.

Acylcarnitines are intermediate metabolites of the mitochondria that serve as biomarkers for inherited disorders of fatty acid oxidation and amino acid metabolism. The prevailing clinical method used to study acylcarnitines involves flow-injection tandem mass spectrometry (FI-MS/MS) with precursor ion scanning. This approach, often called “acylcarnitine profile analysis”, is associated with a number of limitations; foremost the inability to separate and therefore distinguish isobaric/isomeric acylcarnitine species.