GC · ALIENTO
SIBO - Breath test (bacterial overgrowth)
Breath test that quantifies exhaled hydrogen and methane to assess small intestinal bacterial overgrowth, including methanogenic patterns (IMO).
Request information- Measures exhaled hydrogen and methane
- Detects methanogens (IMO) that H₂-only tests miss
- Serial samples over 2-3 hours
Description
The SIBO breath test assesses small intestinal bacterial overgrowth by measuring the gases produced by the fermentation of an orally administered substrate. When an abnormal microbial density exists in the small intestine, fermentation of the substrate generates an early gas peak that is detected in the breath.
The usual substrate is lactulose (10 g) or glucose (75 g), depending on the clinical indication.
Why methane must also be measured
The distinguishing feature of this test is that it quantifies both hydrogen (H₂) and methane (CH₄). Methane production by methanogenic archaea —now described as IMO (intestinal methanogen overgrowth)— is frequently associated with constipation and goes unnoticed in tests that only measure hydrogen. Measuring both gases avoids false negatives in methanogenic patients.
Method
Gas chromatography
Serial breath samples are analysed by gas chromatography. The system quantifies three gases —hydrogen, methane and CO₂—; the latter is used to correct the quality of each sample and normalise the values.
Indicative thresholds: a rise of H₂ ≥20 ppm above baseline and CH₄ ≥10 ppm. Cut-off points are always interpreted within the clinical context and in light of the full curve.
Sample
Serial breath
Collection of breath samples at several time points over 2-3 hours after ingestion of the substrate. Prior dietary preparation is required according to the instructions to ensure the validity of the result.
Results
H₂ and CH₄ curves
The report presents the time curves of both gases and their interpretation against the thresholds. Within an integrated panel (metagenomic NGS + functional biochemistry), the AI assistant Sophia relates the gas pattern to the microbiota profile and functional markers for a comprehensive reading of the intestinal axis.
You can combine this test with others of the digestive axis in the integrated profiles.
Clinical indications
Suspected overgrowth
- Abdominal distension and excess gas
- Persistent diarrhoea or constipation
- Recurrent postprandial discomfort
Gas pattern differentiation
- Predominant hydrogen pattern
- Methane pattern (IMO) associated with constipation
- Follow-up after antibiotic or dietary treatment