• quality control
• safety
• automation

The intended use of the automatic photometric determination of the icteric index (II) on serum and plasma samples is to provide fundamental information about the sample quality, in relation to analytical procedures that are interfered by bilirubin present at concentrations higher than the established interference thresholds.1 An additional interesting use of the determination of II, first proposed by Salinas et al,2 is its use as front-line test for the identification of blood samples with abnormal total bilirubin (TB) concentrations. The application of an optimal cut-off for II that reliably identifies abnormal TB concentrations allowed the accurate ‘zero-cost’ detection of samples with normal TB concentrations (ie, ≤0.012 g/L or ≤20.5 µmol/L), avoiding direct measurements in ~40% of bilirubin orders.3 In our laboratory, the use of II for the screening of hyperbilirubinaemic samples was validated in 2015 using the Abbott Architect c16000 analytical system and, since June 2016, serum and plasma samples with a request of TB determination and an II ≤0.8 are automatically reported as having a TB concentration ≤0.012 g/L (≤20.5 µmol/L), without any further measurement.4 The II cut-off value of 0.8 on the Architect c system was demonstrated to have a sensitivity ≥99% for discriminating between specimens with high or normal TB, with a false negative rate of 0.1% on serum samples and 0.2% on plasma samples, respectively.4 The implementation of this reflex testing procedure raised the responsibility of laboratory …