[The 13C-methacetin breath test for quantitative noninvasive liver function analysis with an isotope-specific nondispersive infrared spectrometer in liver cirrhosis].

Background And Objective: Cytochrome-P450-dependent liver function can be measured with the 13C-methacetin breath test (MBT). This has heretofore been done with the use of a mass-spectrometer. This study was undertaken to evaluate the MBT (NDIRS) done with the isotope-selective nondispersive infrared 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 histologically confirmed liver cirrhosis (Child-Pugh stage A [n = 7], B [n = 5] or C [n = 4]) were given 13C-methacetin in 100 ml of tea after a 12-hour fasting 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 ratio of 13C to 12C was determined, as delta (/1000), and from it the maximal percentage rate (PDRmax) calculated, as well as the cumulative rate (cPDRmax) after 30, 60, 120 and 180 min (Median and 5th and 95th percentiles).

Results: For patients with liver cirrhosis there were significantly lower values for cPDRmax and cPDR after 30, 60, 120 and 180 min than in the healthy subjects (P < 0.002): PDR [%]/h: 3.9 (0.7-15.9) vs. 36.5 (23.1-50.0); cDPR 30 min [%]: 1.1 (-0.2-6.0) vs. 12.4 (7.6-17.1); cDPR 3 h [%]: 9.8 (-2.3-27.5) vs. 36.0 (29.9-45.1). There were significant differences among the patients, depending on their Child-Pugh staging.

Conclusion: The MBT with the cost-effective NDIRS can reliably and noninvasively distinguish between healthy subjects and patients with liver cirrhosis. The test is therefore suitable for the quantitative analysis of liver functions.