In post-hepatic jaundice, the concentation of conjugated bilirubin in the blood is higher than that of unconjugated bilirubin because –
## Core Concept
Post-hepatic jaundice, also known as obstructive jaundice, occurs due to a blockage in the bile ducts, preventing bilirubin from being excreted into the intestine. This condition leads to an accumulation of conjugated (direct) bilirubin in the blood. The liver conjugates bilirubin in the form of glucuronides, making it water-soluble.
## Why the Correct Answer is Right
The correct answer, , implies that the concentration of conjugated bilirubin in the blood is higher than that of unconjugated bilirubin in post-hepatic jaundice because the liver's ability to conjugate bilirubin continues, but the obstruction prevents the conjugated bilirubin from being excreted into the bile and subsequently into the intestine. As a result, conjugated bilirubin builds up in the blood. This process involves the enzyme **UDP-glucuronyltransferase**, which conjugates bilirubin.
## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not directly address why conjugated bilirubin levels are higher than unconjugated bilirubin levels in post-hepatic jaundice.
- **Option B:** This option is incorrect as it does not provide a valid reason related to the biochemical or physiological changes occurring in post-hepatic jaundice.
- **Option D:** This option is incorrect because it does not accurately reflect the pathophysiological changes seen in post-hepatic jaundice.
## Clinical Pearl / High-Yield Fact
A key point to remember is that in post-hepatic jaundice, the **bilirubin levels are predominantly elevated in the conjugated (direct) form**. This condition often presents with **jaundice, dark urine, and clay-colored stools** due to the lack of bilirubin pigments in the intestine.
## Correct Answer Line
**Correct Answer: C.**