Contrasting liver function test patterns in obstructive jaundice due to biliary strictures [corrected] and stones

Area of Science:

• Hepatology
• Gastroenterology
• Clinical Biochemistry

Background:

• Obstructive jaundice is commonly associated with elevated alkaline phosphatase (ALP).
• The role of aspartate transaminase (AST) in differentiating causes of obstructive jaundice is less understood.
• Distinguishing between malignant strictures and gallstones as causes of jaundice is clinically important.

Purpose of the Study:

• To compare liver function tests (LFTs), specifically ALP and AST, in patients with obstructive jaundice.
• To differentiate LFT patterns between obstructive jaundice caused by malignant strictures versus gallstones.
• To assess the diagnostic utility of AST and ALP in identifying the etiology of biliary obstruction.

Main Methods:

• A comparative study involving 207 jaundiced patients undergoing endoscopic retrograde cholangio-pancreatography (ERCP).
• Patients were categorized into three groups: malignant strictures, common bile duct stones, and recent stone passage.
• Liver function tests (LFTs), including bilirubin, AST, and ALP, were measured before ERCP and at specific time points for the gallstone groups.

Main Results:

• Patients with malignant strictures showed significantly higher median levels of bilirubin, AST, and ALP compared to those with gallstones.
• In malignant strictures, ALP elevation exceeded AST elevation.
• In gallstone disease, AST and ALP elevations were similar, with AST potentially exceeding ALP during peak jaundice, hyperbilirubinaemia, and pain episodes.

Conclusions:

• The common belief that ALP rises more than AST in obstructive jaundice is accurate for malignant strictures.
• In obstructive gallstone disease, AST may rise equally or even exceed ALP, particularly during acute episodes.
• Elevated AST as the predominant enzyme in obstructive jaundice warrants consideration of extrahepatic biliary obstruction, such as gallstones.