Pathogenesis of hepatolithiasis based on the analysis of components of intrahepatic stones.

Background/aims: It has been thought that intrahepatic stones are brown pigment stones (bilirubin carbonate stones) but we analyzed a chemical compound to reveal that intrahepatic stones have unique components, and studied their pathogenesis.

Methodology: A total of 45 gallbladder stones (15 cholesterol stones, 15 black pigment stones, and 15 brown pigment stones) and 15 intrahepatic stones were analyzed about amounts of fatty acids, bile acids and trace elements in the gallstones. Thus we established the characteristic components of the intrahepatic stones and studied their pathogenesis.

Results: Concerning the amounts of free fatty acids contained in the gallstones, comparing the 247.2 +/- 116.3 mg/g in the brown pigment stones to the 382.8 +/- 176.3 mg/g in the intrahepatic stones, demonstrates a significant difference between the two groups (p = 0.0191). The ratio of free saturated fatty acids/free unsaturated fatty acids was 1.3 +/- 0.5 in the cholesterol stones, 1.3 +/- 0.6 in the black pigment stones, 5.2 +/- 2.8 in the brown pigment stones and 8.3 +/- 3.5 in the intrahepatic stones (p = 0.0086).

Conclusions: It became clear that the intrahepatic stones contained high levels of free bile acids and that bacterial infection, which deconjugates the glycine and taurine conjugations, is involved in the pathogenesis of gallstones. The fatty acid analysis demonstrated high levels of free saturated fatty acids in the gallstones as well as the involvement of phospholipases, which break down phospholipids in bile, particularly phospholipase A1.