Markers of cholestasis

• Alkaline phosphatase

• Gamma-glutamyl transferase (y-GT)

Bilirubin is derived from Hb released from erythrocyte breakdown and conjugated with glucuronide by the hepatocytes. The conjugated fraction is water-soluble whereas the unconjugated fraction is lipid-soluble. Levels are increased with intra- and extrahepatic biliary obstruction (predominantly conjugated), hepatocellular damage and haemolysis (usually mixed picture). Jaundice is detected when levels >45pmol/l.

Alkaline phosphatase is released from bone, liver, intestine and placenta. In the absence of bone disease (check Ca2 + and PO43-) and pregnancy, raised levels usually indicate biliary tract dysfunction.

A raised y-GT is a highly sensitive marker of hepatobiliary disease. Increased synthesis is induced by obstructive cholestasis, alcohol, various drugs and toxins, acute and chronic hepatic inflammation.

0 0

Post a comment