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.

Authors

Miwa A, Morioka I, Yokota T, Shibata A, Matsuo K, Fujioka K, Koda T, Morikawa S, Nishio H, Yokoyama N, Nakamura H, Matsuo M, Yamada H

Institution

Department of Pediatrics, Kobe University Graduate School of Medicine, Japan.

Source

Clinical laboratory 58:5-6 2012 pg 507-14

MeSH

Bilirubin
Diagnostic Techniques and Procedures
Female
Gestational Age
Humans
Infant, Newborn
Infant, Premature
Kernicterus
Male
Neonatal Screening
Peroxidases
Reproducibility of Results
Term Birth
United States
United States Food and Drug Administration

Pub Type(s)

Clinical Trial
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22783582