Elevated carbon dioxide in exhaled breath induces false-positive DOB results during Helicobacter pylori detection with ¹³C-urea breath test using infrared spectroscopy.

@article{fan2026elevated,
  title = {{Elevated carbon dioxide in exhaled breath induces false-positive DOB results during Helicobacter pylori detection with ¹³C-urea breath test using infrared spectroscopy.}},
  author = {Wentao Fan and Yuwen Tao and Jinjin Shi and Zixiang Huang and MeiHong Chen and Guoxin Zhang and Bo Hao and Feng Ye},
  journal = {BMC gastroenterology},
  year = {2026},
  month = jul,
  doi = {10.1186/s12876-026-05169-7},
  url = {https://europepmc.org/article/MED/42897461},
  note = {CC BY-NC-ND},
}

TY  - JOUR
TI  - Elevated carbon dioxide in exhaled breath induces false-positive DOB results during Helicobacter pylori detection with ¹³C-urea breath test using infrared spectroscopy.
AU  - Wentao Fan
AU  - Yuwen Tao
AU  - Jinjin Shi
AU  - Zixiang Huang
AU  - MeiHong Chen
AU  - Guoxin Zhang
AU  - Bo Hao
AU  - Feng Ye
PY  - 2026
DA  - 2026/07/01
JO  - BMC gastroenterology
DO  - 10.1186/s12876-026-05169-7
UR  - https://europepmc.org/article/MED/42897461
AB  - Background  The urea breath test (UBT) detects Helicobacter pylori (H. pylori) by measuring ¹³CO₂ in exhaled air after the ingestion of a ¹³C-urea metabolized by bacterial urease. However, the influence of CO₂ concentrations in exhaled breath on UBT results remains unclear. This study aimed to evaluate the effect of varying exhaled CO₂ levels on the outcomes of infrared spectroscopy-based ¹³C-UBT.Methods  Six 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.Results  A 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).Conclusion  Elevated 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.
SN  - 1471-230X
ER  -