13C-methacetin breath test for monitoring hepatic function in cirrhotic patients before and after liver transplantation

Background: In patients with chronic liver disease, the measurement of liver function is critical for monitoring disease progression, predicting the prognosis and choosing therapeutic strategies. The C-13-methacetin breath test is a simple, non-invasive diagnostic tool based on an inexpensive, non-toxic substance, which allows the accurate measurement of liver functional reserve. Aim: To investigate the C-13-methacetin breath test as a tool to monitor hepatic function in liver transplant candidates and recipients. Methods: Twenty-eight cirrhotic patients listed for orthotopic liver transplantation and 10 healthy controls were studied. The C-13-methacetin breath test (75 mg per os) was performed at baseline and at 12-week intervals. Intra-operative measurements were obtained during the liver transplantation procedure in nine patients. Results were expressed as the C-13-methacetin cumulative oxidation percentage 45 min after substrate ingestion. Results: The mean C-13-methacetin cumulative oxidation at 45 min was 16.4 +/- 3.5% in healthy controls and 5.4 +/- 4.2% in cirrhotic patients at the time of listing. In 11 patients who underwent successful liver transplantation, mean oxidation increased from 3.3 +/- 1.6% before transplantation to 17.0 +/- 5.2% at 6 months of follow-up. Variations in methacetine oxidation were closely related to the recovery of liver function. The mean intra-operative C-13-methacetin cumulative oxidation increased from 0.1% during the anhepatic phase to 3.7 +/- 2.0% 2 h after reperfusion. Conclusions: The C-13-methacetin breath test is a simple and potentially useful tool for monitoring hepatic function in cirrhotic patients listed for liver transplantation, and during the intra-operative and post-operative phases.