The NUNM SIBO Lab now offers both lactulose and glucose SIBO breath tests. Both tests are manufactured by QuinTron Instrument Company. These tests offer the advantages of non-invasive and widely available laboratory tests, compared to the more invasive and less widely-available gold standard testing of small bowel aspiration and quantitative culture.
SIBO Breath tests involve the patient consuming a carbohydrate substrate (either lactulose or glucose) to measure the production of hydrogen and methane gases which are produced solely by bacteria through fermentation of the substrate. Lactulose is a synthetic disaccharide manufactured by VistaPharm which cannot be absorbed by humans. This enables lactulose to travel the entire length of the small intestine and detect SIBO that only occurs in the distal portion of the small intestine. Since glucose is readily absorbed by humans, as a result glucose is thought to be unable to reach the distal portion of the small intestine in the majority of cases.
Each test has different pros and cons and both are useful depending on clinical needs. The glucose breath test has a lower rate of false-positive results compared to the lactulose breath test and is often used for diagnosing proximal SIBO as well as for patients with rapid orocecal transit. The lactulose test is often used to diagnose distal SIBO and for patients with carbohydrate malabsorption. Interpretation of test results for both tests must be considered in conjunction with other factors, including the patient’s adherence to prep guidelines, symptom presentation, and clinical history.