Abstract
The isodecyl neopentanoate is an ingredient used in the cosmetic industry to prepare a nipple fissure balm. We report on 12 newborns that showed elevated C5-acylcarnitine levels upon newborn screening following treatment with balm. The first 3 neonates were immediately recalled for confirmatory tests and resulted negative for both isovaleric acidemia and short/branched chain acyl-CoA dehydrogenase deficiency. In the other 9 cases, the immediate recall was avoided by applying a new second-tier test able to confirm the presence of pivaloylcarnitine. The concentration of C5-acylcarnitine was measured in the days following the suspension of balm application. Abnormal concentrations of C5-acylcarnitine did not seem to be associated with free carnitine deficiency, probably due to the short time of exposure. A direct correlation between balm ingestion and the elevation in pivaloylcarnitine has been demonstrated in 10 adult volunteers. The commercial balm containing a pivalic acid derivative is causal of false-po...
Highlights
Acylcarnitine profile analysis using the flow injection analysis–tandem mass spectrometry (MS/MS) method is commonly used in newborn screening programs for the biochemical screening of fatty acid oxidation and organic acid metabolism disorders
Twelve of the 32 neonates showed abnormal C5acylcarnitine concentrations due to indirect absorption of isodecyl neopentanoate originating from a nipple fissure balm used by nursing mothers to prevent rhagades
In the experiences of Tuscany and Sicily, the biomarker C5acylcarnitine is not causative of many recalls during newborn screening; the positive predictive value of the biomarker is not good (2 isovaleric acidemia (IVA) of the 32 positives corresponding to 6.25%)
Summary
Acylcarnitine profile analysis using the flow injection analysis–tandem mass spectrometry (MS/MS) method is commonly used in newborn screening programs for the biochemical screening of fatty acid oxidation and organic acid metabolism disorders. The profile is analyzed in positive-ion mode, usually using a precursor ion scan experiment or a multiple reaction monitoring (MRM) experiment. A common fragment (85 m/z) containing the quaternary ammonium function could be detected with high sensitivity and specificity. Flow injection analysis–MS/ MS methods cannot distinguish between isobaric compounds, making chromatographic separation essential when the separation of isomers is required for the differential diagnosis of some inborn errors of metabolism.[1,2]. Several authors have developed methods for the determination of C4-acylcarnitine and C5-acylcarnitine isomers in plasma and dried blood spots (DBSs) by ultra-performance.
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