Neonatal Presentations of Metabolic Disorders

Metabolic disorders in a neonate can present with involvement of any organ system and can be challenging to diagnose. A newborn can present with an acute metabolic crisis such as hyperammonemia or seizures needing immediate management, with a more chronic clinical picture such as cholestatic liver disease, or with structural abnormalities such as skeletal manifestations. Early detection of treatable metabolic conditions is important to improve outcomes. Newborn screening has facilitated early detection and initiation of therapy for many metabolic disorders. However, normal testing does not rule out a metabolic disorder and a high index of suspicion should remain when caring for any critically ill neonate without a diagnosis. Whole exome sequencing (WES) or whole genome sequencing (WGS) can be powerful tools in rapid diagnosis of a potentially treatable metabolic condition in a critically ill neonate. This review presents classic clinical presentations of neonatal metabolic disorders and also highlights some uncommon neonatal manifestations of metabolic disorders to improve the recognition and diagnosis of these conditions.