ArticleBMC gastroenterology2026
Elevated carbon dioxide in exhaled breath induces false-positive DOB results during Helicobacter pylori detection with ¹³C-urea breath test using infrared spectroscopy.
Article in BMC gastroenterology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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Abstract
backgroundThe urea breath test (UBT) detects Helicobacter pylori (H. pylori) by measuring
methodsSix volunteers confirmed to be H. pylori-negative via ¹³C-UBT and stool antigen assay were enrolled. All participants completed overnight fasting and oral rinsing before specimen collection, followed by standardized breath sampling with three breath-holding durations (5 s, 10 s, and 20 s). Baseline samples were collected at 0 min, followed by a 30-min rest without ¹³C-urea administered, then test samples were collected. Following each sampling cycle, participants rested with spontaneous quiet breathing for 20-30 s before performing the next breath-holding procedure. Each participant completed 30 sampling cycles, yielding 30 paired baseline-test samples per individual. CO₂ concentrations and delta over baseline (DOB) values were measured using three independent infrared spectrometers under calibration settings of 5.0 and 6.0. A DOB value ≥ 4 was defined as a positive result. High CO₂ was defined as a test-sample CO₂ concentration greater than or equal to the corresponding calibration concentration plus 0.2.
resultsA total of 180 paired baseline-test datasets were included in the analysis. At calibration concentrations of 5.0, positive results were observed in 104 of 118 high CO₂ datasets (88.14%; 95% exact CI, 80.90%-93.36%), whereas none of the 62 low CO₂ datasets showed positive result (0.00%; 95% exact CI, 0.00%-5.78%). At a calibration concentration of 6.0, positive results occurred in 20 of 26 high-CO₂ datasets (76.92%; 95% exact CI, 56.35%-91.03%), whereas all 154 low CO₂ datasets tested negative (0.00%; 95% exact CI, 0.00%-2.37%). Sample-level Fisher's exact tests were significant at both settings (both P < 0.001).
conclusionElevated CO₂ concentrations may be associated with false-positive DOB results in infrared spectroscopy-based ¹³C-UBT, particularly when test-bag CO₂ exceeds the calibration value by more than 0.2 units. Monitoring of exhaled CO₂ during specimen collection is essential to guarantee accurate results.
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