C-13-methacetin breath test with an isotope-selective nondispersive infrared spectrometer for the quantitative noninvasive analysis of hepatic functions in liver cirrhosis

Background and objective: Cytochrome-P450-dependent liver function can be m easured with the C-13-methacetin breath test (MBT). This has heretofore bee n done with the use of a mass-spectrometer. This study was undertaken to ev aluate the MBT (NDIRS) done with the isotope-selective nondispersive infrar ed spectrometer. Patients and methods: 20 healthy volunteers (ten women, ten men, aged 22-76 years) and 16 patients (ten women, six men, aged 48 - 71 years) with histo logically confirmed liver cirrhosis (Child-Pugh stage A [n = 7], B [n = 5] or C [n = 4]) were given C-13-methacetin in 100 mi of tea after a 12-hour f asting period. Breath tests were performed before the test drink and 5, 10, 15, 20, 30, 40, 50, 60, 80, 100, 120, 150 and 180 min thereafter. The rati o of C-13 to C-12 was determined, as delta (parts per thousand), and from i t the maximal percentage rate (PDRmax) calculated, as well as the cumulativ e rate (cPDR(max)) after 30, 60, 120 and 180 min (Median and 5th and 95th p ercentiles). Results: For patients with liver cirrhosis there were significantly lower v alues for cPDR(max) and cPDR after 30, 60, 120 and 180 min than in the heal thy subjects (P < 0.002): PDR [%]/h: 3.9 (0,7-15,9) vs. 36,5 (23.1-50.0); c DPR 30 min [%]: 1.1 (-0.2-6.0) vs. 12.4 (7.6-17.1); cPDR 3 h [%]: 9.8 (-2.3 -27.5) vs. 36.0 (29.9-45.1). There were significant differences among the p atients, depending on their Child-Pugh staging. Conclusion: The MBT with the cost-effective NDIRS can reliably and noninvas ively distinguish between healthy subjects and patients with liver cirrhosi s. The test is therefore suitable for the quantitative analysis of liver fu nctions.