Stability of ¹³C-Urea Breath Test Samples Over Time in the Diagnosis of Helicobacter pylori

Background: The accuracy and repeatability of breath test in the diagnosis of Helicobacter pylori infection have not been adequately investigated. Although it has been shown that storage for long periods does not affect the analysis results, no data are available on the effect of repetitive testing. In this study, our aim was to evaluate the repeatability of the analyses of breath samples at room temperature. Methods: A total of 202 positive breath samples were collected in duplicates, before and after administration of 75 mg ¹³C- urea dissolved in 100 ml of orange juice. Breath test results were expressed as delta ¹³CO₂. The cut-off value was 3.5 parts per thousand. Each sample was analyzed in a mass spectrometer 7, 14, 21, and 28 days after collection. The accuracy calculation was based on the comparison of the delta ¹³CO₂ obtained in the three consecutive weeks following the first test run to the delta ¹³CO₂ obtained in the first test run. Results: Two hundred (99%), 197 (97.52%), and 196 (97%) of the 202 samples tested positive in the second, third, and fourth test runs, respectively. The accuracy of the delta ¹³CO₂ was 98.6%, 99.2%, and 96.7% in the three consecutive runs, respectively. Conclusion: Short-term storage of 1 month does not affect sample stability or the results of ¹³C-urea breath tests in up to three consecutive repeats.