Stability of acylcarnitines and free carnitine in dried blood samples: implications for retrospective diagnosis of inborn errors of metabolism and neonatal screening for carnitine transporter deficiency.

Objective: Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) is increasingly used in newborn screening programs. Acylcarnitine profiles from dried blood spots (DBS) are used to detect fatty acid oxidation disorders, carnitine cycle disorders, and organic acidurias. Stored dried blood is also a valuable source for postmortem investigations to unravel the cause of unexplained death in early childhood.

Metabolic effects of intravenous LCT or MCT/LCT lipid emulsions in preterm infants.

Most lipid emulsions for parenteral feeding of premature infants are based on long-chain triacylglycerols (LCTs), but inclusion of medium-chain triacylglycerols (MCTs) might provide a more readily oxidizable energy source. The influence of these emulsions on fatty acid composition and metabolism was studied in 12 premature neonates, who were randomly assigned to an LCT emulsion (control) or an emulsion with a mixture of MCT and LCT (1:1). On study day 7, all infants received [13C]linoleic (LA) and [13C]alpha-linolenic acid (ALA) tracers orally.