What is the Trio-Smart (Triple Smart) Testing Hydrogen Methane Breath Test?

Trio-Smart Testing Hydrogen Methane Breath Test

The Trio-Smart breath test is a non-invasive diagnostic tool that measures hydrogen, methane, and hydrogen sulfide gases in exhaled breath to help diagnose small intestinal bacterial overgrowth (SIBO), but it has poor sensitivity and specificity and is not recommended as a primary diagnostic test for SIBO according to current guidelines. 1

What is the Trio-Smart Breath Test?

• Trio-Smart is a breath test that simultaneously measures three gases: hydrogen, methane, and hydrogen sulfide in exhaled breath after consumption of a substrate (typically glucose or lactulose) 2, 3
• It aims to identify bacterial overgrowth in the small intestine by detecting gas production from bacterial fermentation of carbohydrates 4
• The test typically involves collecting breath samples at baseline and at intervals after consuming the substrate, with measurements analyzed to determine if there is evidence of SIBO 5

Scientific Basis and Limitations

• Hydrogen breath testing is based on the principle that some bacteria ferment carbohydrates, producing hydrogen gas that is absorbed into the bloodstream and exhaled 1
• Methane measurement was added to improve sensitivity, as 3-25% of individuals are non-hydrogen producers 1, 3
• Hydrogen sulfide has been more recently added to potentially identify additional cases of SIBO, particularly in constipation-predominant patients 6
• The British Society of Gastroenterology explicitly states that both glucose and lactulose hydrogen breath tests have poor sensitivity and specificity and are not recommended for the diagnosis of SIBO 1

Diagnostic Accuracy

• Recent studies show that glucose breath testing had sensitivity less than 50% compared with duodenal aspirate (the gold standard), regardless of whether methane measurement was added 1
• Both positive and negative predictive values for breath testing were less than 70% in comparative studies 1
• A 2024 study found that glucose breath testing showed better agreement with jejunal aspirate culture (κ = 0.659) than lactulose breath testing (κ = 0.588) 5
• When using combined hydrogen-methane testing, specificity can reach 85% with accuracy of 71.7% 2

Clinical Application

• Despite limitations, breath testing remains the most widely utilized non-invasive diagnostic modality for suspected SIBO 3
• The test is preferred over empirical antibiotic treatment to support antibiotic stewardship and establish a clear diagnosis 7
• For patients who cannot undergo breath testing, endoscopic small bowel aspiration for qualitative assessment is the recommended alternative 7
• Interpretation should consider that transit time variability can lead to false positive results 1

Important Considerations and Caveats

• Culture of small bowel aspirates remains the most sensitive test for SIBO, though methods are poorly standardized 1
• False negative results may occur in non-hydrogen producers or with variable intestinal transit 1
• The utility of concurrent hydrogen and methane breath testing with measurements of orocaecal transit time could potentially reduce false positive diagnoses, but has not been subject to definitive clinical study 1
• In patients with high clinical suspicion of SIBO but negative testing, empirical antibiotic trial may be considered 1
• Recent evidence suggests that cut-off values for positivity may need adjustment: fasting CH4≥5 ppm, or CH4≥4 ppm and H2≥24 ppm may be more accurate than traditional thresholds 2

Treatment Implications

• If SIBO is diagnosed, rifaximin 550 mg twice daily for 1-2 weeks is the most effective treatment, with 60-80% efficacy 8, 7
• Alternative antibiotics include doxycycline, ciprofloxacin, amoxicillin-clavulanic acid, and cefoxitin 8
• For recurrent SIBO, rotating antibiotics with 1-2 week periods without antibiotics may be effective 8
• Dietary modifications to reduce fermentable carbohydrates may help manage symptoms 9