Correlation And Precision of Serum Free Bilirubin Concentrations Determined by Single And Two Peroxidase Concentration Methods in Term or Late-Preterm Newborn Infants Using a FDA-Approved Analyzer
Miwa, A.; Morioka, I.; Yokota, T.; Kiyomi, A.Matsuo, S.; Fujioka, K.; Koda, T.; Morika, S.
Clinical Laboratory 58(5-6): 507-514
2012
ISSN/ISBN: 1433-6510 PMID: 22783582 Document Number: 11795
Background: Free bilirubin concentration (B f ) is an index for identifying newborns at risk for developing bilirubin-induced neurotoxicity. It has been suggested that B f measured by a single peroxidase concentration (B f-single ) does not equal the equilibrium concentration of B f , which is confirmed by B f at two different peroxidase concentrations (B f-two ). However, the differences between B f-single and B f-two are unknown in the serum of term or late-preterm newborn infants. Furthermore, to apply B f-single with savings on time and cost to the clinical setting, it is very important for us to clarify the differences between B f-single and B f-two . Methods: Forty serum samples were obtained from 21 term or late-preterm newborns who were admitted at Kobe University Hospital. Using a peroxidase method, B f-single was measured at one peroxidase concentration, and B f-two was determined at two different peroxidase concentrations (the manufacturer's recommended peroxidase concentration and half the manufacturer's recommended peroxidase concentration). To clarify the relationship between B f-single and peroxidase concentrations, B f-single was measured at five different concentrations of peroxidase reagent. Intra-day and inter-day analyses were performed to assess the precision of B f-single and B f-two . Results: 1/B f-single increased as peroxidase concentration increased. B f-single was significantly lower than B f-two (B f-single : 0.50 μg/dL [0.13 - 1.22 μg/dL] versus B f-two : 0.59 μg/dL [0.15 - 1.76 μg/dL], p f-single was significantly correlated with B f-two (r = 0.953, p f-two and 3.3% for B f-single , and the inter-day CV was 12.4% for B f-two and 3.2% for B f-single . Conclusions: Although B f-single and B f-two are not identical, B f-single is significantly correlated with B f-two and it is more precise than B f-two in term or late-preterm newborns.
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