Increased C3 Acylcarnitine Concentration in a Newborn

A 2-week-old (term) female was brought to the emergency room following newborn screening results showing increased C3 acylcarnitine, (16.7 μmol/L; reference interval, u003c4.5 μmol/L). She was admitted for further evaluation. Acylcarnitine profile in plasma, repeated using tandem mass spectrometry (MS/MS),2 confirmed the high C3 result (10.6 μmol/L; reference interval, u003c0.87 μmol/L). The child was asymptomatic and was growing and developing normally with no concerns. A urine sample was collected for organic acids analysis by GC-MS (Fig. 1).Fig. 1. Organic acids analysis of patient urine using GC-MS.Urine organic acids were extracted into ethyl acetate/ether and converted to trimethylsilyl (TMS) derivatives prior to analysis using an Agilent GC 6890N/MS 5975 system equipped with a DB-1 column.This child has methylmalonic acidemia (MMA), a term used to describe a group of metabolic disorders biochemically characterized by the accumulation of methylmalonic acid in body fluids. In addition to the production of methylmalonic acid, these disorders are further subclassified based on …