Feasibility of a breath test with a substrate of natural 13C-abundance and isotope-selective non-dispersive infrared spectrometry: a preliminary study.

BACKGROUND AND AIMS: Isotope-selective non-dispersive infrared spectrometry (NDIRS) is a cheaper alternative to isotope ratio mass spectrometry (IRMS). We checked on the efficiency of NDIRS to perform a breath test with naturally (13)C-enriched maize starch.
METHODS: Fifty-six healthy volunteers were examined. After a basal fasted sample of their expiratory air was collected, the subjects ate a test breakfast of 50 g (CF50 group, n = 9) or 100 g (CF100 group, n = 47) cornflakes with 175 g yoghurt. For 6 h thereafter, exhaled air was collected every 30 min for the NDIRS measurement of (13)CO(2) concentration.
RESULTS: The time-course of the curves of (13)CO(2) concentration resembled those obtained previously with IRMS. A dose-response to the amount of ingested cornflakes was observed--the maximum postprandial net increment in (13)CO(2) was statistically significantly higher in the CF100 than CF50 group: 4.78 +/- 0.13 versus 3.12 +/- 0.17 per thousand (P < 0.001), whereas the time needed to reach the maximum did not differ after the intake of 50 g (233 +/- 13 min) or 100 g (248 +/- 9 min) cornflakes. The 5-h area-under-the-curve of cumulative (13)CO(2) net recovery (AUC(60-360)) was statistically significantly greater after ingestion of 100 g compared to 50 g cornflakes (97.6 +/- 2.2 versus 61.7 +/- 2.2 micromol, P < 0.001) and it also exhibited a stable between-subject variability.
CONCLUSION: The obtained proof of technical feasibility of a breath test with the use of naturally (13)C-enriched starch and NDIRS provides background for future research on the clinical usefulness of this method for a non-invasive assessment of the pancreatic exocrine function.