Effects of bilirubin photoisomers on the measurement of direct bilirubin by the bilirubin oxidase method. (March 2018)

• Record Type: Journal Article
• Authors: Okada, Hitoshi; Kawada, Kou; Itoh, Susumu; Ozaki, Miyo; Kakutani, Isami; Arai, Takeshi; Koyano, Kosuke; Yasuda, Saneyuki; Iwase, Takashi; Murao, Koji; Kusaka, Takashi
• Is Part Of: Annals of clinical biochemistry. Volume 55:Number 2(2018:Mar.)
• Page Start: 276
• Page End: 280
• Publication Date: 2018-03
• Subjects: Direct bilirubin -- bilirubin oxidase -- cyclobilirubin -- bilirubin photoisomer; Clinical chemistry -- Periodicals; Clinical biochemistry -- Periodicals; 616.075
• DOI: 10.1177/0004563217716474
• Languages: English
• ISSNs: 0004-5632

Abstract

Background: We occasionally encounter increases in direct bilirubin value on reanalysis of the surplus serum collected in the past from a neonate with indirect hyperbilirubinemia. But the details of this phenomenon are unclear. We evaluated the change of direct bilirubin and the relation of bilirubin photoisomer of the serum exposed to room light. Methods: Surplus serum samples from neonates with indirect hyperbilirubinemia were exposed to room light for 24 h. The bilirubin fraction assay of samples was performed by the bilirubin oxidase method (Nescauto and Aqua-auto Kainos reagent) and high-performance liquid chromatography. Results: Direct bilirubin increased significantly from 0.61 to 2.36 mg/dL. The respective ratios of bilirubin photoisomers before and after exposure were as follows: cyclobilirubin (0.007 to 0.29) and (EZ)-bilirubin (0.018 to 0.041) increased significantly, (ZZ)-bilirubin decreased 0.84 to 0.55 significantly. The difference of the cyclobilirubin concentration was most closely associated with those of the direct bilirubin concentration. Conclusion: Direct bilirubin value was increased after exposure to the room light, and increase in direct bilirubin was significantly correlated by cyclobilirubin increase in the serum samples from neonates with indirect hyperbilirubinemia.