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Updated: Jun 5, 2026

Biochemical Measurement of Neonatal Hypoxia
Published on: August 24, 2011
Unbound bilirubin and bilirubin-albumin binding levels of Japanese neonates
Kazuki Nishizawa1, Yoshinori Katayama2, Yong-Kye Lee3
1Department of Neonatology, Takatsuki General Hospital, Takatsuki, Osaka, Japan.
Objective:
To determine postnatal changes in total serum bilirubin (TB), unbound bilirubin (UB), and bilirubin-binding affinity of albumin (Ka) among Japanese newborns.
Study Design:
In a retrospective study, we evaluated for serum TB, UB, and albumin (Alb) levels, and their calculated UB/TB ratios, and Ka in 786 neonates born ≥36 weeks' gestation and analyzed to subcategories of three postnatal epochs: first, second, and ≥third weeks.
Result:
TB levels were significantly higher (p < 0.01) at age ≥three weeks, while UB levels were significantly higher (p < 0.01) in the first week. UB/TB ratios were significantly lower while calculated Ka values were significantly higher as age-in-weeks increased (p < 0.01).
Conclusion:
Hyperbilirubinemia in the first and second weeks of age in neonates born ≥36 weeks' gestation is associated with higher UB levels or UB/TB ratios with lower Ka and may potentially contribute to the risk of developing bilirubin neurotoxicity with aggravated variations in bilirubin, albumin and Ka.
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