Biliary obstruction leads to an increase in which type of bilirubin?

• A. Unconjugated bilirubin
• B. Direct bilirubin
• C. Conjugated bilirubin
• D. Total bilirubin

Answer: (C)

Biliary obstruction causes an increase in conjugated bilirubin due to the inability of bile to flow from the liver to the intestine. Normally, bilirubin produced from the breakdown of red blood cells is transported to the liver, where it is conjugated to a water-soluble form for excretion into the bile. When there is a blockage in the biliary system, this conjugated bilirubin accumulates in the liver and eventually spills into the bloodstream, leading to increased levels of conjugated bilirubin.

Since conjugated bilirubin is more water-soluble, it can enter the bloodstream even when the bile flow is impaired, resulting in a measurable elevation observed in laboratory tests. This is typically associated with conditions such as cholestasis or biliary duct obstruction, where the conjugated form is not able to reach the intestine as it normally would.

In contrast, while total bilirubin levels may rise (since they include both unconjugated and conjugated bilirubin), the specific increase due to biliary obstruction is primarily in the conjugated form. Unconjugated bilirubin levels are generally more elevated in conditions causing increased hemolysis rather than obstructive processes in the biliary system. Therefore, the correct and most relevant answer in the context of bili