Which bilirubin fraction is predominant during necrotic liver disease?

In necrotic liver disease, the predominant bilirubin fraction is unconjugated bilirubin. This occurs because liver cell necrosis can disrupt the liver's ability to effectively process bilirubin.

Unconjugated bilirubin is produced from the breakdown of hemoglobin and is normally taken up by the liver, where it is then converted into conjugated bilirubin through a process called conjugation. When the liver is damaged, as it is during necrotic conditions, this processing is impaired, leading to an accumulation of unconjugated bilirubin in the bloodstream.

This rise in unconjugated bilirubin might be accompanied by symptoms such as jaundice, as the liver struggles to convert this bilirubin into its water-soluble form for excretion. In contrast, conjugated or direct bilirubin would typically be elevated in cases of biliary obstruction or certain types of liver disease that primarily affect bilirubin processing after conjugation has occurred. This distinction highlights why unconjugated bilirubin is the primary fraction observed during necrotic liver disease.