Laboratory Markers in the Diagnosis of Intrahepatic vs Extrahepatic Cholestasis

Clinical Pearls

• Pattern recognition is key:
  • Intrahepatic cholestasis → hepatocellular enzymes (AST/ALT) rise alongside cholestatic markers.
  • Extrahepatic cholestasis → disproportionate rise in ALP + GGT, with conjugated hyperbilirubinemia.
• Confirmatory imaging (ultrasound, MRCP, ERCP) is essential to localize obstruction.
• Functional tests (PT correction with vitamin K) can help distinguish malabsorption (extrahepatic) vs hepatocellular synthetic failure (intrahepatic).

Test
Intrahepatic Cholestasis
Extrahepatic Cholestasis

Serum Bilirubin
Mixed (conjugated + unconjugated) elevation
Predominantly conjugated (direct) bilirubin

Alkaline . . .