Determination of total bilirubin in whole blood from neonates: results from a French multicenter study

Background: Jaundice is frequent in neonates and can cause severe complications, especially in premature neonates, particularly the risk of developing acute bilirubin encephalopathy. Our purpose was to verify if determination of total bilirubin (TBIL) in whole blood on an ABL™ 735 blood gas analyzer with a spectrophotometer module could provide an analytical alternative to chemical methods of TBIL measurement. Methods: Our multicenter comparative study involved four hospital laboratories. We studied the repeatability and reproducibility of ABL 735 TBIL measurements in two control sera of medium (N1, 58.1 μmol/L) and high (N2, 275.3 μmol/L) TBIL levels. The same study was simultaneously conducted on four chemistry instruments (two LX 20®, one Integra 800® and one Hitachi 917®) using four Jendrassik-Grof derived methods. At one site, repeatability was performed with two adult whole-blood samples containing low and high TBIL levels (55.1 and 312.6 μmol/L). Results: Repeatability tests provided coefficients of variation (CVs) between 0.67% and 1.86% on the ABL 735 system, vs. 0.35% and 1.96% for the chemistry instruments. Reproducibility tests for the same control sera resulted in CVs between 1.01% and 3.55% for the ABL 735 and between 0.52% and 3.65% for the chemistry instruments. Recovery for the N1 and N2 control sera was 102-120%. A correlation study of TBIL determination in whole blood vs. plasma was conducted on 473 neonatal blood samples. Correlation coefficients between whole blood and plasma TBIL ranged from 0.969 to 0.994. Passing-Bablok equations were y=1.17x+9.7 [site 1 (IP)], y=1.01x+ 5.6 [site 2 (JPB, MR)], and y=1.00x-20 [site 3 (AS)]. Only 10% of the results fell outside the 10% range in the bias-corrected Bland-Altman difference plot for the ABL 735 method compared to traditional laboratory methods. Conclusions: The ABL 735 instrument is reliable for measuring TBIL in 70-μL whole blood samples from neonates. Thus, this method might allow significant blood savings in preterm neonates. Correlation with the reference method for plasma or sera must be established to ensure good follow-up of patients.