CATALIN VICTOR SFARTI, ALIN CIOBICA, CAROL STANCIU, GHEORGHE G. BALAN, IRINA GARLEANU, ANCA TRIFAN OXIDATIVE STRESS STATUS IN PATIENTS WITH CHOLEDOCHOLITHIASIS: BEFORE AND AFTER ENDOSCOPIC SPHINCTEROTOMY AND BILIARY CLEARANCE Choledocholithiasis may cause biliary obstruction which leads to hepatocellular injury. Oxidative stress has been proposed as a possible mechanism involved in this disorder. This study evaluates the oxidative stress burden in patients with choledocholithiasis and secondary cholestasis, before and after endoscopic sphincterotomy. Experimental part: Patients diagnosed with choledocholithiasis and secondary extrahepatic cholestasis were included in the study between January 1st 2016 and October 31st 2016. In all patients oxidative stress markers were collected within 2 hours before and 48 hours after therapeutic ERCP. Selected markers were superoxide dismutase (SOD), glutathione peroxidase (GPX) and malondialdehyde (MDA). The results were compared to those from a group of 40 healthy subjects. Significantly lower concentrations of SOD (p = 0.03) and GPX (p < 0.0001) activities, associated with an increased level of MDA level (p < 0.0001) were shown in patients before biliary clearance compared with the healthy control group. After ERCP the only oxidative stress parameter which showed improvement was the SOD specific activity (p = 0.037). This study shows that extrahepatic cholestasis secondary to choledocholithiasis is associated with increased oxidative stress status. After biliary clearance one oxidative stress marker was significantly improved (SOD), suggesting a possible antioxidant effect of such procedure.