Effect of hemolyzed plasma on the batch measurement of nitrate by nitric oxide chemiluminescence.

cepted reference method for total bilirubin determination is currently available. Thus, the widely used DPD procedure was chosen as the comparison method in this study. Quality specifications in terms of precision and accuracy met CLIA (11 ) as well as European regulatory requirements (12 ). In the patient samples, the measured bilirubin values covered the physiologically relevant range (85–400 mmol/L) within which decisions on phototherapy or exchange transfusion have to be made (2, 5). In general, there was a good agreement between bilirubin concentrations measured in plasma by the DPD method and those obtained from whole blood by multiple-wavelength photometry. The slope of the regression line was close to 1, and no significant systematic bias between the two methods was observed. There was, however, a rather wide spread of data around the regression line. Thus, correlation was considerably weaker than desirable for equivalent methods. On the basis of the withinand betweensubject biologic variability of bilirubin [CVwithin 5 25.6% and CVbetween 5 30.5%, respectively (13 )], the desirable imprecision (CV) and bias can be calculated to be ,13% and ,10%, respectively. Thus, the desirable total error should be ,31.1% (13 ). In our study, these quality requirements were met in 86% of cases. In conclusion, determination of total bilirubin from whole blood by multiple-wavelength photometry on a blood gas analyzer is a promising method for point-ofcare testing. It combines the advantages of small sample volume and fast turnaround time. The manufacturer is currently working on an update of the measurement algorithm.