• Abdominal bloating: Persistent or recurring bloating, especially after meals.
• Abdominal discomfort: Cramping, pain or a feeling of digestive pressure.
• Gas or belching: Excessive gas, belching or digestive sounds.
• Altered bowel habits: Constipation, diarrhoea or fluctuating patterns.
• Nausea: Intermittent queasiness or unsettled digestion.
• Fatigue: Low energy or tiredness that appears alongside digestive symptoms.
• Food-related reactions: Sensitivity or discomfort after certain foods.
• Skin symptoms: Flushing, irritation or breakouts that accompany gut changes.
• Head discomfort: Headaches or a sense of head pressure.
• Joint discomfort: Aching, stiffness or intermittent joint sensitivity.
• Digestive difficulty: Signs of poor digestion or reduced nutrient tolerance.
• Unintentional weight changes: Weight loss or changes in appetite without a clear reason.
• Mood changes: Irritability, low mood or emotional variation that occurs with digestive symptoms.
• SIBO-related concerns: When upper–small-intestine SIBO or early fermentation patterns are suspected.

Overview

The SIBO with Glucose Breath Test measures hydrogen and methane levels during a timed breath collection to assess fermentation patterns in the upper small intestine. These gases are produced when undigested carbohydrates interact with bacteria, and their appearance in exhaled air can help indicate whether bacterial activity is occurring higher in the digestive tract than expected. Hydrogen elevation may suggest hydrogen-dominant SIBO, while methane elevation may indicate methane-producing organisms, sometimes referred to as intestinal methanogen overgrowth (IMO). Because glucose is rapidly absorbed, this method primarily reflects bacterial activity in the proximal small intestine.

The test may be clinically useful when symptoms such as bloating, abdominal discomfort, irregular bowel habits, nausea or fatigue are present. By analysing changes in hydrogen and methane throughout the collection period, the profile offers an overview of digestive fermentation patterns that may contribute to these presentations. Glucose provides a targeted assessment of early small intestinal fermentation.

The SIBO breath test provides a practical way to review hydrogen and methane trends alongside symptoms and case history. The findings can help inform further investigation or guide decisions related to digestive comfort, carbohydrate tolerance and small intestinal function.

Practical

Specimen

Breath

Container

• Vacuum-sealed collection tubes

Patient preparation

• Requires fasting 12 hours prior to collection
• This test will take 3 hours to complete
  
• Preparation for the test starts 2-4 weeks before collection ( Please check sample collection instructions)

Please note this test will take 3 hours to complete. 

Research

Research

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• Erdogan A, Rao SSC. Small Intestinal Fungal Overgrowth. Current Gastroenterology Reports. 2015;17(4).

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• Gabbard S, Lacy B, Levine G, Crowell M. The impact of alcohol consumption and cholecystectomy on small intestinal bacterial overgrowth. Digestive diseases and sciences. 2013;59(3):638–44.

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• Hauge T, Persson J, Danielsson D. Mucosal bacterial growth in the upper gastrointestinal tract in alcoholics (heavy drinkers). Digestion. 2009;58(6):591–595.

• Lauritano E, Gabrielli M, Scarpellini E, et al. Small intestinal bacterial overgrowth recurrence after antibiotic therapy. The American journal of gastroenterology. 2008;103(8):2031–5.

• Levitt MD. Volume and Composition of Human Intestinal Gas Determined by Means of an Intestinal Washout Technic. New England Journal of Medicine. 1971;284(25):1394-1398.

• Lloyd-Still JD, Shwachman H. Duodenal microflora. The American Journal of Digestive Diseases. 1975;20(8):708-715.

• Methodology and Indications of H2-Breath Testing in Gastrointestinal Diseases: the Rome Consensus Conference. Alimentary Pharmacology & Therapeutics. 2009;29:1-49.

• Newberry C, Tierney A, Pickett-Blakely O. Lactulose Hydrogen Breath Test Result Is Associated with Age and Gender. BioMed Research International. 2016;2016:1-5.

• Rana S, Sharma S, Kaur J, Sinha S, Singh K. Comparison of Lactulose and Glucose Breath Test for Diagnosis of Small Intestinal Bacterial Overgrowth in Patients with Irritable Bowel Syndrome. Digestion. 2012;85(3):243-247.

• Rana SV, Bhardwaj SB. Small intestinal bacterial overgrowth. Scandinavian Journal of Gastroenterology. 2008;43(9):1030-1037.

• Roland B, Ciarleglio M, Clarke J, et al. Small intestinal transit time is delayed in small intestinal bacterial Overgrowth. Journal of clinical gastroenterology. 2014;49(7):571–6.

• Saad RJ, Chey WD. Breath Testing for Small Intestinal Bacterial Overgrowth: Maximizing Test Accuracy. Clinical Gastroenterology and Hepatology. 2014;12(12):1964-1972.

• Shah ED, Basseri RJ, Chong K, Pimentel M. Abnormal Breath Testing in IBS: A Meta-Analysis. Digestive Diseases and Sciences. 2010;55(9):2441-2449.