13C-Phenylalanine and 13C-Methacetin breath test to evaluate functional capacity of hepatocyte in chronic liver disease

Background, To grade liver damage, Child-Pugh classification is used but these tests do not reflect the quantitative functional hepatic reserve. Aims. C-13-Phenylalanine Breath Test and C-13-Methacetin Breath Test are evaluated as possible tools, being both safe and easy to perform, to quantify functional hepatic reserve in chronic liver disease patients. Patients. Both tests were performed in 48 healthy volunteers and 48 chronic liver disease patients. Methods. Breath samples were collected after taking C-13-Phenylalanine (100 mg) and C-13-Methacetin (75 mg). (CO2)-C-13 enrichment was measured using mass spectrometry. Results. Both tests discriminated the hepatic function, decreasing results of the (CO2)-C-13, enrichment agreeing with the increasing severity of the hepatic patient (C-13-Phenylalanine Breath Test multiple correlation coefficient: 0.72, global p<0.001; Methacetin Breath Test: 0.73, p<0.001). Correlation between C-13-Phenylalanine Breath Test and Methacetin Breath Test was 0.63, p<0.001. If both tests were pathological, the sensitivity for the diagnosis of hepatic dysfunction was high (98%), although the specificity decreased to 60%. Best results were obtained at 30 minutes with C-13-Phenylalanine Breath Test and at 10 minutes with Methacetin Breath Test. Conclusions. Both C-13-Phenylalanine Breath Test and Methacetin Breath Test are safe and easy tests to perform and both are able to discriminate the hepatic functional capacity between the different groups studied.