Assessment of Neonatal Hyperbilirubinemia Using GEM Premier 4000 Total Bilirubin Assay

Abstract

The American Academy of Pediatrics recommends measurement of total bilirubin (TBili) in newborns to assess the risk of developing severe neonatal hyperbilirubinemia and bilirubin-induced neurologic dysfunction. In this study, we evaluated the correlation of whole blood TBili results measured on a blood gas analyzer to serum results obtained on an automated chemistry analyzer. In addition, we determined the concordance of hyperbilirubinemia risk classification between the 2 methods. Seventy-nine blood samples were collected. The TBili (mg/dL) was measured on whole blood using the Instrumentation Laboratories GEM 4000 (GEM) and on simultaneously collected serum samples on the Siemens Dimension Vista chemistry analyzer (Vista). Twenty-four infants, aged younger than 7 days, were classified into categories for risk of sequelae of severe hyperbilirubinemia using an established postnatal hour-specific nomogram. GEM results showed a mean bias of +0.55 mg/dL compared with Vista. Eight (33%) of 24 infants were assigned different risk grades by the GEM; 4 were assigned higher risk grades, and 4 had lower risk grades; only 1 infant’s risk status was changed by more than 1 grade. Therefore, although the GEM method shows good overall agreement with the Vista chemistry analyzer in measurement of TBili levels, assignment of clinical risk categories may differ by the 2 methods.