Abstract
Stability of bilirubin was investigated under various temperature conditions (-20°C, 4°C, 25°C, 37°C) with or without lighting for 7 days.
The values of direct bilirubin and total bilirubin (direct bilirubin+indirect) decreased gradually as the temperature and/or time increased.
The ratio of the direct bilirubin to the total bilirubin changed little at-20°C or 4°C, but gradually lowered at 25°C over time (p< 0.05).
This was caused by the increase of unconjugated bilirubin (Bu) and the decrease of diconjugated bilirubin (dBc), monoconjugated bilirubin (mBc) and δ-bilirubin (Bδ).
When illuminated with light, bilirubin changed to photobilirubin or biliverdin etc., and the values of direct bilirubin and total bilirubin rapidly decreased. The ratio of direct bilirubin to total bilirubin increased with time. These results indicate that the photobilirubin is derived from Bu in indirect bilirubin, and it is hydrous bilirubin.
