It is well understood that transient elevations in specific acylcarnitine species on the newborn screen can actually originate from the infant’s mother. Often times this is thought to be due to an occult inborn error of metabolism, such as a mother with asymptomatic 3-methylcrotonyl-CoA carboxylase deficiency. However, I have often wondered how other clinical modifiers might contribute to false positive newborn screens. Ryckman et al just published in J Matern Fetal Neonatal Med. 2013 Apr 3 that C0, C2, C8:1, and C18:2 acetylcarnitines were elevated in infants born to preeclamptic mothers. This group also observed similar elevations in small for gestational age infants and in infants where labor was not initiated prior to delivery. More of these types of retrospective studies are important in understanding the potential reasons for false positives on the newborn screen.
Hilary Vernon, MD PhD