After recalibration of a total serum bilirubin assay in 2012, mean maximum TSB levels, clinically significant hyperbilirubinemia, and phototherapy use all decreased significantly.
In 2012, the maker of a commonly used reflectance spectrophotometry assay for total serum bilirubin (TSB) in neonates (Ortho Clinical Diagnostics; Vitros BuBc assay) adjusted calibration values to address concerns that results were biased. To evaluate the effect of this change, investigators at a large healthcare system in California compared TSB levels and use of phototherapy between roughly 62,000 infants born during a 28-month period before the recalibration and 43,000 born during a 19-month period after recalibration.
TSB was measured within the first 30 days in 99.5% of infants. The mean maximum TSB level decreased from 10.1 mg/dL before recalibration to 8.8 mg/dL after recalibration. Concurrently, the proportion of infants with TSB lev…