Performance and Interpretation of Hydrogen and Methane Breath Testing Impact of North American Consensus Guidelines

Dig Dis Sci. 2022 Dec;67(12):5571-5579. doi: 10.1007/s10620-022-07487-8. Epub 2022 Apr 2.


Background: Hydrogen and methane breath tests (HMBT) are widely used clinical investigations but lack standardization. To address this, the North American Consensus (NAC) group published evidence-based recommendations for HMBT.

Aims: To evaluate results obtained using NAC recommendations for HMBT, compared to retrospective data that utilized guidelines previously recommended.

Methods: HMBT data from 725 patients referred for small intestinal bacterial overgrowth (SIBO) and/or carbohydrate malabsorption (CM) testing were analyzed. Data were compared regarding dose of substrate for SIBO testing (16 vs. 10 g lactulose, and 50 vs. 75 g glucose) and the effect of post-ingestion sampling period for malabsorption testing. The effect of different recommended cut-off values for SIBO were examined.

Results: Substrate dose did not affect methane production. 10 g lactulose significantly reduced positive SIBO results compared to 16 g lactulose (42 vs. 53%, p = 0.04). 75 g glucose significantly increased positive results compared to 50 g glucose (36 vs. 22%, p = 0.04). Provoked symptoms were significantly more prevalent in patients testing positive by both North American Consensus and Ledochowski cut-off values. 34.5% of patients tested positive for CM at 180-min compared to 28% at 120-min (not significant, p = 0.19).

Conclusions and inferences: 10 g lactulose substrate produces fewer positive SIBO results than 16 g lactulose, while 75 g glucose dose produces more positive SIBO results than 50 g. Performing CM breath tests for 180 min increases number of positive results when compared to 120 min. SIBO cut-off timings require further investigation, but our findings broadly support the NAC recommendations for SIBO and CM testing.

Keywords: Breath tests; Fermentation; Lactulose; Microbiome; Small intestine.

MeSH terms

  • Breath Tests / methods
  • Glucose
  • Humans
  • Hydrogen*
  • Intestine, Small / microbiology
  • Lactulose*
  • Methane
  • North America
  • Retrospective Studies


  • Lactulose
  • Hydrogen
  • Methane
  • Glucose