Serum β-N-acetyl hexosaminidase and bile acid levels in patients with benign and malignant biliary obstruction

β-N-Acetyl hexosaminidase (β-NAH), a lysosomal enzyme, was measured in the plasma of 15 patients with malignant extrahepatic biliary obstruction, 14 with benign extrahepatic obstruction, and 15 with long- standing benign intrahepatic cholestasis. β-NAH was correlated with total serum bile acid levels. The correlation was significant (P<0.05) for the malignant and benign intrahepatic obstructions but not for the benign extrahepatic obstructions. This is consistent with the idea that circulating high levels of bile acids in patients with long-standing biliary obstruction may cause damage to Kupffer cell membranes and to their receptors for β-N-acetyl hexosaminidase, impeding the clearance of the enzyme from the circulation resulting in elevated serum levels.