In this issue of JAMA Pediatrics, Kuzniewicz et al1 describe the consequences of an in vitro diagnostics manufacturer altering the values assigned to their calibrators for the determination of neonatal bilirubin concentrations. Notable in the study are the sizes of the prerecalibration population (n = 61 945) and postrecalibration group (n = 47 359). This significantly large number of newborn samples was evaluated for exceeding the American Academy of Pediatrics phototherapy threshold and the effect on phototherapy of newborns during their birth hospitalization and its effect on readmission for phototherapy. The postrecalibration resulted in patient bilirubin levels decreasing by 1.18 mg/dL (to convert to micromoles per liter, multiply by 17.1) and consequently decreasing the number of infants above the American Academy of Pediatrics phototherapy threshold. Changes to bilirubin assays are not limited to reassigning values to calibrators. Changes to different manufactured lots of reagents is very common, while changing to an alternate bilirubin assay is uncommon.2 Even instrumentation changes may result in new bilirubin assays that may occur more frequently owing to the consolidation of health systems and the need for clinical laboratories to standardize their instrumentation.
Stanley F. Lo. Laboratory Accuracy in Neonatal BilirubinThe Search for Truth in Laboratory Medicine. JAMA Pediatr. 2016;170(6):529–530. doi:10.1001/jamapediatrics.2016.0279