Background & aims: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in many parts of the world. The ¹³C-methacetin breath test (MBT), a microsomal liver function test, enables quantitative evaluation of cytochrome P450-dependent liver function involved in NAFLD pathogenesis. The aim of our study was to evaluate the efficacy of MBT in differentiating patients with non-alcoholic steatohepatitis (NASH) from patients with simple steatosis (SS) and its ability to predict significant fibrosis in NAFLD patients.
Methods: We performed MBT in 64 patients with histologically proven NAFLD (ranging from SS to severe steatohepatitis) and in 20 healthy controls. Brunt scoring system for histological evaluation of NAFLD served as a reference. The correlation between MBT parameters and liver biopsy was tested using Spearman's coefficient. The overall validity was measured using the area under the receiver operating characteristic curve (AUROC) with 95%CI.
Results: ¹³C-MBT is a good tool for identifying patients with histologically proven NASH, with an AUROC of 0.824, 95% CI (0.723-0.926), a sensitivity of 95% and a specificity of 74%. The diagnosis accuracy of ¹³C-MBT for significant fibrosis (F ≥2) has a validity of 91% (95% CI, AUROC = 0.830-0.989) with higher sensitivity (90%) and specificity (81%). ¹³C-MBT values predicted better F3 or F4 fibrosis (AUROC were 0.936 and 0.973).
Conclusion: Due to the impairment of microsomal function which occurs in NAFLD, ¹³C-MBT could be a reliable diagnostic and follow-up test for NAFLD patients.