Twenty-minute fasting version of the US ¹³C-urea breath test for the diagnosis of H. pylori infection

Background. In large-scale multi-center clinical trials, the US ¹³C-urea breath test (UBT) has proven to have a sensitivity and specificity of approximately 95%. Ingestion of a meal to delay gastric emptying has advantages of increasing the level of signal as well as prolonging the duration of significantly increased ¹³C excretion, at the expense of requiring 40 to 60 minutes to complete the test. Our aim was to explore the utility of the ¹³C-UBT with a total duration of 30 minutes or less. Methods. After a baseline breath sample was obtained, 125 mg of ¹³C-urea was given in 100 ml of water, and additional breath samples were taken after 20 and 30 minutes. The results of the UBT were compared to histological assessment, culture, and the rapid urease test. ¹³C-UBTs were carried out on normal volunteers who underwent gastroscopy during which six mucosal biop-sies were taken. Three biopsies were for histological evaluation (Genta stain), two for culture, and one was for agar gel rapid urease testing. The UBT was conducted 2 to 3 days either before or after the endoscopic procedure. Results. The cutoff value for a positive UBT was enrichment of 2.4Δ‰ (delta over baseline). Of the 66 tests, 51‰ were Helicobacter pylori-positive. There were no false positive UBTs and only two false negative UBTs at 20 minutes (sensitivity, 96%; specificity, 100%). At 30 minutes, one other UBT was false negative (gray zone of 2.36‰) (sensitivity, 94%; specificity, 100%). Conclusion. These results suggest that omission of the meal and shortening the duration of the US ¹³C-UBT to 20 minutes still may maintain excellent specificity and sensitivity of the test.