Serum Bilirubin Optical Measurement Adjusted for Oxyhemoglobin: Calibration Procedure Development for Portable Point-of-Care Bilirubinometers

This study proposes a calibration procedure for a portable point-of-care (POC) bilirubinometer that adjusts optical measurements of total blood bilirubin by accounting for the interference caused by oxyhemoglobin concentration. For this purpose, a neonatal POC bilirubinometer was used, and optical measurements were conducted at 455 and 575 nm wavelengths on samples containing different concentrations of bovine total serum bilirubin (TSB): 0, 16.7, 12.8, 8.4, 5.3, 3.1 mg/dL) and human-derived oxyhemoglobin (O2Hb: 0, 5, 10, 20, 40, 80 mg/dL). The voltage outputs from these samples were used to generate a calibration curve. In the pure TSB samples, the accuracy was ±0.08 mg/dl, the precision was 0.32 mg/dL, and the mean absolute percentage error (MAPE) was 23.9%. When using the model that incorporates samples with both TSB and O2Hb, the accuracy increased at ±0.04 mg/dL, the precision to 0.30 mg/dL, and the MAPE to 15.4%, showing a significant improvement in measurement performances when the O2Hb interference is taken in consideration. The study concludes that incorporating O2Hb concentrations into the calibration procedure for neonatal POC bilirubinometers significantly reduces interference and enhances the accuracy and precision of TSB concentrations.