13C-galactose breath test and 13C-aminopyrine breath test for the study of liver function in chronic liver disease

Background & Aims: Liver biopsy examination is the gold standard to diagnose the presence of cirrhosis. The aim of this study was to evaluate the accuracy of both C-13-aminopyrine breath test (C-13-ABT) and C-13-galactose breath test (C-13-GBT) in the noninvasive assessment of the presence of cirrhosis in patients with chronic liver disease. Methods: We evaluated 61 patients with chronic liver disease of diverse etiologies (21 compensated cirrhosis). All patients underwent C-13-GBT and C-13- ABT, and the results were expressed as a percentage of the administered dose of C-13 recovered per hour (%dose/h) and as the cumulative percentage of administered dose of C-13 recovered over time (%dose cumulative). Results were analyzed according to absence vs presence of cirrhosis. Results: On average, C-13-GBT %dose/h and %dose cumulative were decreased significantly in patients with compensated cirrhosis, and the same finding was observed for C-13-ABT results from 30 to 120 minutes. C-13-GBT %dose/h at 120 minutes had 71.4% sensitivity, 85.0% specificity, and 83.7% accuracy, whereas C-13-ABT %dose cumulative at 30 minutes had 85.7% sensitivity, 67.5% specificity, and 77.1% accuracy for distinguishing between the 2 subgroups of patients. Combined assessment of C-13-GBT and C-13-ABT increased the diagnostic accuracy (80% positive predictive value) of either test alone and reached 92.5% specificity and 100% sensitivity for the diagnosis of cirrhosis. Conclusions: In patients with chronic liver disease, both C-13-GBT and C-13-ABT are useful for the diagnosis of cirrhosis. Combination of the tests increases the diagnostic yield of each test alone.