The role of ¹³C-methacetin breath test for the non-invasive evaluation of nonalcoholic fatty liver disease.

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.