Reducing the False-Positive Rate for Isovalerylcarnitine in Expanded Newborn Screening: The Application of a Second-Tier Test

• Autor(a) principal: Poggiali,Sara
• Data de Publicação: 2016
• Outros Autores: Ombrone,Daniela, Forni,Giulia, Malvagia,Sabrina, Funghini,Silvia, Mura,Massimo, Pasquini,Elisabetta, Santoro,Laura, Bellavia,Vincenzo, Granata,Orazia Maria, Castana,Cinzia, McGreevy,Kathleen S., Aronica,Tommaso Silvano, Marca,Giancarlo la
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of Inborn Errors of Metabolism and Screening
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2326-45942016000100311
• topic: newborn screening; tandem mass spectrometry; false positive; pivalic acid; second-tier test

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-positive results during newborn screening, and it could have the potential to cause secondary carnitine deficiency when used chronically.