Neonatal total bilirubin measurements: Still room for harmonization.

BACKGROUND: Universal screening of total bilirubin in neonates is endorsed by experts from the American Academy of Pediatrics and is increasingly common. Methodological differences between diazo-based quantitation ("wet" chemistry) and reflectance spectrophotometric quantitation ("dry" chemistry) can lead to unnecessary treatment. A recent recalibration of the only commercially available "dry" chemistry assay was issued to reduce these differences. This study evaluated the post-recalibration bias between the two assay types.

METHODS: Method comparison of neonatal total bilirubin (Beckman AU680 vs Ortho-Clinical-Diagnostics Vitros) was achieved using freshly-drawn neonatal samples (n=239).

RESULTS: The Vitros produced neonatal bilirubin results with a 12.4% average positive bias compared to the AU680 total bilirubin results. The AU680 direct bilirubin reaction had 5.6% cross reactivity with unconjugated bilirubin.

CONCLUSIONS: Neonatal or total bilirubin quantitation remains unharmonized between platforms. Care should be taken to understand the bias of specific platforms.