Which enzyme is not typically used as a secondary marker for obstructive jaundice?

• A. GGT
• B. 5'NT
• C. Ornithine Carbamoyl Transferase
• D. ALT

Answer: (D)

In obstructive jaundice, the problem is a blockage of bile flow, so the labs that reflect cholestasis rise. Markers such as gamma-glutamyl transferase (GGT) and 5'-nucleotidase (5'NT) increase because they’re associated with bile duct injury and cholestasis. Alkaline phosphatase (ALP) also typically rises in this pattern. These enzymes help indicate obstruction rather than direct liver cell injury.

ALT, by contrast, is a hepatocellular enzyme released when liver cells are damaged. Its level doesn’t specifically indicate obstruction and can be normal or only mildly elevated in pure cholestasis. That’s why ALT isn’t used as a secondary marker for obstructive jaundice.

Ornithine carbamoyl transferase isn’t a standard marker for this condition either; it’s a urea cycle enzyme, not a primary indicator of cholestasis.