A) Quantitative evaluation of liver function by the methionine and aminopyrine breath tests in the early stages of liver transplantation

OBJECTIVE: The early phase after liver transplant is considered the period of greatest risk for graft failure. In recent years breath tests have been proposed as a non-invasive method to assess liver function. In particular, the aminopyrine breath test is useful for evaluating the liver viable mass, and the methionine breath test could be used to evaluate oxidative capacity of liver mitochondria. We aimed to perform these tests in the early phase following liver transplant in order to correlate the time course of these tests to the outcome of transplantation. METHODS: Twenty-three patients undergoing liver transplant were enrolled. The methionine and aminopyrine breath tests were performed on the days 1, 3 and 5, and 2, 4 and 6, respectively, after transplant. Results were expressed as the percentage of administered 13C recovered per hour and as the cumulative percentage of the 13C dose recovered over the test period. RESULTS: All but two transplants were successful in the short term and the cumulative percentage of the dose of 13C progressively increased after transplantation, reaching values not significantly different from controls (methionine at day 5). In two patients, primary non-function occurred: in these patients the cumulative percentage of the 13C dose did not increase after orthotopic liver transplant and the results of both breath tests indicated that it always remained significantly lower compared to that of other patients. CONCLUSIONS: A combination of breath tests, exploring both mitochondrial and microsomal function, could be useful in the early phase after liver transplant in order to evaluate the graft outcome.