Liver function breath tests for differentiation of steatohepatitis from simple fatty liver in patients with nonalcoholic Fatty liver disease.

Goals: We investigated the utility of liver function breath tests [C-Aminopyrine Breath Test (C-ABT), C-Galactose Breath Test (C-GBT)], for the diagnosis of nonalcoholic steatohepatitis (NASH) among nonalcoholic fatty liver disease (NAFLD) patients.

Background: Liver biopsy is currently the gold standard for the differentiation between simple fatty liver (NAFL) and NASH in NAFLD patients.

Materials And Methods: Thirty-six patients with histologically proven NAFLD (NAFL:16, NASH:20) underwent C-ABT and C-GBT. The results were expressed as the percentage of administered C dose recovered per hour (%dose/h) and as cumulative percentage of administered C dose recovered over time (%cumulative dose). Histologic lesions were scored according to Brunt and Kleiner's classifications.

Results: C-ABT results correlated inversely with activity grade (r=-0.650, P=0.001), NAFLD activity score (r=-0.473, P=0.026), and fibrosis stage (r=-0.719, P=0.001). Compared with NAFL, NASH patients had significantly lower %dose/h and %cumulative dose at 60, 90, and 120 minutes (always P<0.04) by C-ABT. C-ABT %dose/h and %cumulative dose at 120 minutes could predict the presence of NASH (area under the receiver operating characteristic curve: 0.762 and 0.741, respectively). In contrast, there was no significant association between C-GBT results and any patient characteristic.

Conclusions: In the NAFLD patients, decreased and delayed liver microsomal function, as assessed by C-ABT, is associated with more severe necroinflammation and fibrosis, whereas C-ABT results at 120 minutes may be helpful for the diagnosis of NASH.