Nondispersive isotope-selective infrared spectroscopy: A new analytical method for C-13-urea breath tests

Background: Currently, stable isotope techniques in breath tests using C-13-labeled substrates are limited to a few centers equipped with expensive and complex isotope ratio mass spectrometry (IRMS). Although breath samples can be mailed to these centers, widespread application of C-13 breath tests would be more feasible with a cheaper and more practicable analysis system at hand. Methods: We therefore tested the newly developed nondispersive isotope-selective infrared spectrometer (NDIRS) with reference to IRMS in a clinical setting comparing the results of both techniques in 538 consecutive C-13-urea breath tests performed for the detection of Helicobacter pylori infection. Results: With NDIRS five false-positive and three false-negative results were observed; that is, the sensitivity of NDIRS was 98.3%, and the specificity was 98.6%. The delta over base-line values of both devices correlated linearly (Y = 0.87 +/- 0.01 X + 0.29 +/- 0.15; r = 0.95; p < 0.0001; n = 538). Conclusions: When running this large number of breath tests in 3 days, the NDIRS proved to be a reliable, stable, and easy-to-operate analytical tool, which is well qualified for gastroenterologic application in the diagnostic routine. Both the price and the easy handling of NDIRS will facilitate the widespread use of the noninvasive stable isotope technique for C-13 breath tests.