Establishing Normal Values For Gastrointestinal Hydrogen Sulphide Production in Breath Using Selected-Ion Flow-Tube Mass Spectrometry (SIFT-MS)

A Hobson1,2,3, S Bloor1,2,3, N Nagalingam4, A Smolinska4, B O’Brien4, R Stallard4, T Woodland4, A Tawfike4, M Allsworth4, B Boyle4

1. Functional Gut Diagnostics

2. The Functional Gut Clinic

3. Anglia Ruskin University

4. Owlstone Medical

Poster PDF

Abstract: 

Introduction: Hydrogen and methane breath testing is well established in terms of analysis techniques, guidelines for test preparation and clinical cut-offs allowing for the diagnosis of Small Intestinal Bacterial Overgrowth (SIBO), Intestinal Methanogen Overgrowth (IMO) and carbohydrate malabsorption. Hydrogen sulphide (H₂S) is another by-product of microbial fermentation that is produced under anaerobic conditions by sulphur reducing gut microbes that can impact gut motility and inflammation. Increased H₂S production has been associated with symptoms of diarrhoea and gastrointestinal disorders such as IBD and IBS. Until recently, current techniques for measuring H₂S reported values in the parts per million (ppm) range which may not be sensitive enough to detect pathological changes. In this study we use SIFT-MS which can detect H₂S in the parts per billion (ppb) range to establish normative values.
Methods: 25 healthy volunteers completed a 3hr lactulose breath test using standard test preparation guidelines. Breath samples were taken at baseline (0 mins) and 45, 90 and 180-minutes post lactulose ingestion. Samples were collected using 500ml polyvinylidene fluoride (PVDF) bags and analysed using SIFT-MS. This was repeated at 28 days post iron supplementation.
Results: H₂S values on visit 1 demonstrated levels in the parts per billion range (mean H₂S = 20 ppb ±5) at baseline and this did not change in response to lactulose ingestion (p=0.62). After 28 days of iron supplementation (visit 2) the amount of H₂S produced at baseline decreased significantly (p=0.027) but no further differences were seen post lactulose. Hydrogen and Methane gases were also measured to confirm intestinal fermentation of the test substrate
Conclusions: We demonstrate that in healthy subjects H₂S can be reliably detected in the ppb range using SIFT-MS. Breath samples remains stable within PVDF bags at up to 7-days post acquisition making this a viable technique for in clinic or home testing. The lack of response to lactulose ingestion in this study may reflect the low prevalence of H₂S production from the healthy microbiome. Further studies in patients with IBD and IBS are now warranted to establish the pathological range of H₂S production.