Routine Metabolic Testing is Not Warranted in Unexpected Infant Death Investigations

Abstract

Inborn errors of metabolism (IEM) only rarely cause sudden unexpected infant death. Yet, postmortem metabolic screening is often ordered reflexively during infant death investigations, even in the absence of historical, clinical or autopsy findings suggestive of IEM. This retrospective descriptive study examines the impact of metabolic screening of infants who die suddenly in a medical examiner's jurisdiction. The study population included 135 cases, one of which was certified as death due to IEM with historical and pathologic findings suggestive of IEM and an abnormal postmortem screening study, one which was certified as death due to IEM with historical and pathologic findings suggestive of IEM and a negative postmortem screening study, and one which was certified as undetermined with pathologic features of IEM and a negative postmortem screening study, but also with features suggestive of accidental asphyxia. Nine cases had abnormal postmortem screens that were deemed to represent false positives. During the entire nine-year study of these 135 cases, the utilization of screening tests in cases without historical or autopsy features of IEM did not detect any unsuspected cases. IEM may rarely cause unexpected infant death, and it can be suggested by historical and autopsy findings. Thus, within the appropriate investigative and autopsy context, judicious use of metabolic screening tests is warranted. Caution is advised when interpreting negative screening studies with suggestive historical and/or autopsy findings as the success of testing decreases with increasing postmortem interval.