GPT and cholecystolithiasis: Notably, two hepatolithiasis patients (BLD5 and BLD6), who also showed evidence of liver damage with elevation of the liver enzyme alanine aminotransferase (ALT; normal range 9–50 U/L; 154 and 110 U/L for BLD5 and BLD6, respectively, Additional file 2: Table S7), displayed prominently higher levels of liver-derived DNA (817 and 649 GE/mL, or 30% and 25% for BLD5 and BLD6, respectively) comparing with patients suffering cholecystolithiasis and choledocholithiasis patients.