[False positive on neonatal screening: C5-carnitin increase in newborns due to pre-labour treatment with cefditoren pivoxil].

The increase in C5-carnitin (C5) quantified by tandem mass spectrometry allows for early detection of isovaleric acidemia (IVA) in newborns. The administration of pro- drugs like cefditoren pivoxil (CFP) composed by pivalic acid esters also causes increases of C5 in blood. This work shows the experience of the Laboratorio de Cribado Neonatal of the Comunidad de Madrid in the newborn screening for IVA.