How are newborns screened for carnitine deficiency?

Updated: Dec 13, 2019
  • Author: Fernando Scaglia, MD, FACMG; Chief Editor: Maria Descartes, MD  more...
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Answer

Newborn screen

  • Primary carnitine deficiency can be identified in infants by expanded newborn screening using tandem mass spectrometry by detection of low levels of free carnitine (C0). In addition, newborns’ low carnitine levels may result from primary carnitine deficiency in their affected mothers.

  • Pediatrician needs to contact the family to inform them of the newborn screening result and ascertain clinical status and whether the newborn presents with poor feeding, lethargy, or tachypnea.

  • Consultation with a pediatric metabolic specialist has to be immediately activated and the newborn should be evaluated for tachycardia, hepatomegaly, or reduced muscle tone. After obtaining confirmatory testing with total and free plasma carnitine levels in the newborn and mother, carnitine supplementation with 100 mg/kg/d by mouth in 3 divided doses should be initiated by the metabolic specialist.

  • Confirmatory and diagnostic testing can be performed with carnitine uptake assay in cultured fibroblasts and SLC22A5 gene sequencing.

  • Clinical availability of SLC22A5 gene sequencing may preclude the need of a skin biopsy and carnitine uptake assay on cultured fibroblasts.

  • The family has to be educated about signs, symptoms and need for urgent treatment if infant becomes ill.


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