OBJECTIVE: The (13)C-urea breath test ((13)C-UBT) is the most accurate non-invasive method for diagnosis of Helicobacter pylori infection. However, several methodological issues have not been resolved yet. The aim of this study was to test different protocols of (13)C-UBT to find the optimal test drink and sampling interval. MATERIAL AND METHODS: (13)C-UBT was performed at 3-day intervals in 27 healthy volunteers using citric acid (test A), orange juice (B) and still water (C) as test drinks. Breath samples were collected from time 5 to 60 min. A total number of 2106 breath samples were analysed by isotope ratio mass spectrometry (cut-off value 3.5). RESULTS: Differences in delta values were greater than would be expected by chance (A versus B and A versus C at times 20, 25, 30, 35 and 40 min, p<0.05, Dunnett's method). There were no grey zone- or false-negative results among H. pylori-positive persons in test A at any time, but some were found in tests B and C. Optimal intervals for breath sampling are at times 20 or 25 min after (13)C-urea ingestion. CONCLUSIONS: Citric acid solution as a test drink and 20- or 25-min breath sampling intervals are optimal for the (13)C-UBT in healthy volunteers.

2nd Department of Internal Medicine Charles University Prague Czech Republic