Low prevalence of positive hydrogen breath tests in patients with functional gastrointestinal conditions and hypermobile Ehlers-Danlos syndrome

Neurogastroenterol Motil. 2023 Sep;35(9):e14570. doi: 10.1111/nmo.14570. Epub 2023 Mar 29.


Background: Using hydrogen breath testing (HBT) to diagnose small intestinal bacterial overgrowth (SIBO) remains controversial in patients with functional gastrointestinal (GI) disorders, and unknown in those with hypermobility Ehlers-Danlos syndrome (hEDS). We assessed prevalence of positive HBTs in these groups, evaluated the predictive value of GI symptoms and the potential role of proton pump inhibitors (PPIs) on test results.

Methods: Sequential patients referred for HBT to a tertiary unit were classified into the following groups: GI maldigestion/malabsorption, GI sensorimotor disorders, hEDS, and functional GI disorders. All underwent standardized HBT, and the yield was assessed against symptoms and PPI use.

Key results: A total of 1062 HBTs were performed over 3 years (70% female, mean age 48 ± 16 years). Overall, 7.5% (80/1062) patients had a positive HBT. Prevalence of positive HBT was highest in patients with GI maldigestion/malabsorption (17.9%; DOR 16.16, p < 0.001), GI sensorimotor disorders (15.9%; DOR 8.84, p < 0.001), compared to functional GI disorders (1.6%; DOR 1.0) (p < 0.0001). None of the hEDS patients tested positive for HBT. A positive HBT was independently associated with increased age (DOR 1.03; p < 0.001) and symptoms of diarrhea (DOR 3.95; p < 0.0001). Patients on PPIs tended towards a positive HBT than patients off PPIs (16.1% vs 6.9%; DOR 2.47; p < 0.0001).

Conclusions & inferences: Less than 2% of patients with functional GI disorders, and none of the patients with hEDS had a positive HBT. Pre-test probability was higher in patients with: GI structural or neurological disorders; use of long-term PPIs and symptoms of diarrhea. These criteria may be helpful in making appropriate therapeutic decisions and avoiding unnecessary hydrogen breath testing.

Keywords: functional gastrointestinal disorders; hydrogen breath testing; hypermobile Ehlers-Danlos syndrome; irritable bowel syndrome; small intestinal bacterial overgrowth.

MeSH terms

  • Adult
  • Breath Tests
  • Diarrhea / diagnosis
  • Diarrhea / epidemiology
  • Diarrhea / etiology
  • Ehlers-Danlos Syndrome* / complications
  • Ehlers-Danlos Syndrome* / diagnosis
  • Ehlers-Danlos Syndrome* / epidemiology
  • Female
  • Gastrointestinal Diseases* / diagnosis
  • Gastrointestinal Diseases* / epidemiology
  • Humans
  • Hydrogen
  • Malabsorption Syndromes*
  • Male
  • Middle Aged
  • Prevalence
  • Proton Pump Inhibitors


  • Hydrogen
  • Proton Pump Inhibitors

Supplementary concepts

  • Ehlers-Danlos syndrome type 3