 This cycle, in addition to the demonstration of the potent antioxidant activity of bilirubin, has led to the hypothesis that bilirubin's main physiologic role is as a cellular antioxidant.Total bilirubin = direct bilirubin + indirect bilirubin

Elevation of both alanine aminotransferase and bilirubin is more indicative of serious liver injury than is elevation in ALT alone, as postulated in Hy's law that elucidates the relation between the lab test results and drug-induced liver injury

The measurement of unconjugated bilirubin is underestimated by measurement of indirect bilirubin, as unconjugated bilirubin (without/yet glucuronidation) reacts with diazosulfanilic acid to create azobilirubin which is measured as direct bilirubin.Direct bilirubin = Conjugated bilirubin + delta bilirubin

In the liver, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase, making it soluble in water