What causes the rise in serum conjugated bilirubin in hepatitis?

The rise in serum conjugated bilirubin in hepatitis is primarily due to defective liver function. In hepatitis, the liver cells (hepatocytes) become damaged and are less able to properly process and excrete bilirubin. Under normal circumstances, bilirubin produced from the breakdown of hemoglobin in red blood cells is taken up by liver cells, where it is then conjugated (made water-soluble) and secreted into the bile for elimination.

When liver function is impaired as seen in hepatitis, the conjugation process is disrupted. This leads to an accumulation of conjugated bilirubin in the bloodstream because the liver cannot effectively clear it. This explains why elevated levels of conjugated bilirubin are often observed in patients with hepatic inflammation or injury.

In contrast, failure of the enterohepatic circulation, excessive hemolysis, and increased consumption of bilirubin are not the primary mechanisms responsible for the rise in conjugated bilirubin during hepatitis. These factors may affect bilirubin levels in other contexts, but in the specific case of hepatitis, the defect lies within the liver’s ability to process bilirubin.