1. 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.
- Author
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Miwa A, Morioka I, Yokota T, Shibata A, Matsuo K, Fujioka K, Koda T, Morikawa S, Nishio H, Yokoyama N, Nakamura H, Matsuo M, and Yamada H
- Subjects
- Bilirubin chemistry, Bilirubin standards, Diagnostic Techniques and Procedures standards, Female, Gestational Age, Humans, Infant, Newborn, Kernicterus blood, Kernicterus diagnosis, Male, Peroxidases chemistry, Reproducibility of Results, United States, United States Food and Drug Administration, Bilirubin blood, Diagnostic Techniques and Procedures instrumentation, Infant, Premature blood, Neonatal Screening instrumentation, Term Birth blood
- Abstract
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 microg/dL [0.13 - 1.22 microg/dL] versus B(f-two): 0.59 microg/dL [0.15 - 1.76 microg/dL], p < 0.001), but B(f-single) was significantly correlated with B(f-two) (r = 0.953, p < 0.0001). Intra-day analysis showed that the CV was 9.7% for B(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.
- Published
- 2012