13C-methacetin breath test in chronic hepatitis C liver disease

BACKGROUND: The 13C-methacetin breath test is a non-invasive method to evaluate hepatic microsomal function that allows a quantitative assessment of the functional hepatic mass. AIM: To evaluate the clinical usefulness of the 13C-methacetin breath test in patients with hepatitis C chronic liver disease. PATIENTS AND METHODS: Seventy eight patients with chronic hepatitis C and 13 matched healthy controls were studied. HCV patients were classified as having chronic hepatitis (n = 51), cirrhosis (n = 27), being seven with decompensated disease (presence of ascite, jaundice and/or encephalopathy). HbsAg/HIV co-infected patients, chronic alcohol drinker, having other chronic diseases and those using drugs that could interfere with hepatic cytochrome P450, were excluded. The disease stage and activity in biopsy fragments were determined according the Brazilian Society of Hepatology criteria. Breath test was performed with 75 mg of 13C-methacetin, and the 13CO2 in the expired air was measured through a nondispersive infra red spectrometry. The delta over baseline, and the cumulative recovery of 13CO2 at 40 (13C-methacetin breath test 40 min) and 120 minutes (13C-methacetin breath test 120 min) were calculated. RESULTS: 13C-methacetin breath test parameters correlate only with hepatic staging but not with necroinflammatory (activity) parameters, being the best correlation found between hepatic staging and the 13C-methacetin breath test 120 minutes. The mean values for 13C-methacetin breath test 120 min was significantly reduced in the cirrhotic groups (19.2 +/- 7.1% for compensated and 14.7 +/- 4.0% for decompensated cirrhotics) than in control (29.9 +/- 4.5%) and chronic hepatitis (27.8 +/- 6.1%) groups. The best diagnostic accuracy for the diagnosis of cirrhosis among HCV patients was found for 13C-methacetin breath test 120 min with 81% of sensibility and 77% of specificity. CONCLUSION: 13C-methacetin breath test is correlated with structural changes in HCV-related chronic hepatic diseases and the cumulative recovery at 120 minutes is a sensitive parameter to identify the presence of hepatic cirrhosis in these patients.