Noninvasive Evaluation of Liver Function in Morbidly Obese Patients

Background. More than half of the obese patients develop nonalcoholic fatty liver disease (NAFLD), which may further progress to nonalcoholic steatohepatitis (NASH) and cirrhosis. The aim of this study was to assess alterations in liver function in obese patients with a noninvasive liver function test. Methods. In a prospective cohort study 102 morbidly obese patients undergoing bariatric surgery were evaluated for their liver function. Liver function capacity was determined by the LiMAx (R) test (enzymatic capacity of cytochrome P450 1A2). Liver biopsy specimens were obtained intraoperatively and classified according to the NAFLD Activity Score (NAS). NASH clinical score was additionally calculated from laboratory and clinical parameters. Results. Median liver function capacity was 286 (IQR=141) g/kg/h. 27% of patients were histologically categorized as definite NASH, 39% as borderline, and 34% as not NASH. A significant correlation was observed between liver function capacity and NAS (r=-0.492; p<0.001). The sensitivity and specificity of the LiMAx (R) test to distinguish between definite NASH and not NASH were 85.2% and 82.9% (AUROC 0.859), respectively. According to the NASH clinical scoring system, 14% were classified as low risk, 31% as intermediate, 26% as high, and 29% as very high risk. Liver function capacity is also significantly correlated with the NASH clinical scoring system (r=-0.411; p<0.001). Conclusions. Obese patients show a diminished liver function capacity, especially those suffering from type 2 diabetes. The liver function capacity correlates with histological and clinical scoring systems. The LiMAx (R) test may be a valuable tool for noninvasive screening for NASH in obese patients.