Small intestinal bacterial overgrowth (SIBO), often used as a blanket term for SIBO and intestinal methanogen overgrowth (IMO), is the accumulation of bacteria in the small intestine. IMO, previously called methane-SIBO, is the overgrowth of methane-producing microorganisms (archaea) in the small or large intestines. SIBO breath tests aid in diagnosing and treating SIBO and IMO by measuring hydrogen and methane gases produced by intestinal microorganisms over 2-3 hours. Hydrogen sulfide gas also contributes to SIBO, and recent advancements in testing now allow us to diagnose hydrogen sulfide-SIBO. This article will discuss the SIBO breath tests available to order through Rupa Health.
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What is SIBO Testing?
SIBO breath testing is a noninvasive testing alternative to small intestinal culture to diagnose SIBO and IMO. A SIBO breath test is performed the morning after a patient follows a restrictive preparatory diet and overnight fast. The test begins with the patient collecting a baseline breath sample and drinking a water mixture containing either glucose or lactulose. The patient then continues collecting breath samples at timed intervals for the test duration, lasting 2-3 hours.
Bacteria and archaea in the gastrointestinal (GI) tract ferment carbohydrates, producing hydrogen, methane, and hydrogen sulfide gases. These gases diffuse into the bloodstream and are exhaled through the lungs. Elevations of gas levels during the SIBO breath test are diagnostic for the overgrowth of bacteria and/or methanogens in the GI tract. Per the North American Consensus, a test is positive if at least one of the following criteria is met (1, 2):
- Hydrogen-SIBO: hydrogen levels rise at least 20 ppm from baseline within the first 90 minutes of the test
- IMO: methane level is at least 10 ppm at any time point during the test
- Hydrogen sulfide-SIBO: hydrogen sulfide level is at least 3 ppm at any time point during the test
There is no universal standard SIBO breath test. Glucose and lactulose breath tests both offer their own benefits. Glucose is absorbed within the first three feet of the small intestine; the advantage of a glucose breath test is that it limits the number of false positive test results, and it can accurately diagnose overgrowth within the proximal small intestine. Humans cannot digest or absorb lactulose; the advantage of a lactulose breath test is that it can diagnose overgrowth in the distal portions of the small intestine, which is thought to be more common. (1)
Which Patients is SIBO Testing Best Used For?
SIBO has been correlated with many digestive and non-digestive symptoms and medical conditions. Over two-thirds of patients with diagnosed SIBO report digestive symptoms, including bloating, abdominal pain, belching, flatulence, indigestion, constipation, and diarrhea. Symptoms can vary in frequency, duration, and severity. Irritable bowel syndrome (IBS) is a functional bowel disorder diagnosed when abdominal pain and irregular bowel movements are present for at least six months. IBS and SIBO/IMO symptoms overlap; data reveal that nearly 80% of patients with IBS have underlying SIBO contributing to their symptoms. (3, 4)
SIBO testing can benefit other patients, too, as SIBO has been associated with a variety of other conditions, including inflammatory bowel disease (IBD), rosacea, restless legs syndrome (RLS), pancreatitis, hypothyroidism, Parkinson's disease (PD), diabetes, and coronary artery disease. Additionally, people who use proton pump inhibitors (PPIs) and opioids are at a higher risk for developing SIBO/IMO. (3)
Rupa Heath's Top 3 Popular SIBO Test Overview
Here is an overview of Rupa Health's Top 3 Most Popular SIBO Test in our reference guide:
SIBO Test from Genova Diagnostics
What Does This Test Measure?
Genova offers a SIBO 2-Hour and 3-Hour lactulose breath test, which both measure hydrogen and methane gas levels in breath samples collected by the patient over a two- or three-hour testing period.
What Makes This Test Popular?
Lactulose breath tests depict SIBO and IMO located in the proximal and distal portions of the small intestine. The SIBO 3-Hour test is the only three-hour SIBO breath test available to order through Rupa Health.
When Should You Consider This Test?
Ordering providers must have prescriptive rights to order Genova's SIBO breath tests. Lactulose breath tests should not be ordered for anyone with a documented lactulose allergy.
The SIBO 3-Hour test is preferred for patients with chronic constipation or slowed intestinal motility. A three-hour breath test is also preferred to assess for colonic IMO.
Trio-smart from Gemelli Biotech
What Does This Test Measure?
The trio-smart breath test measures hydrogen, methane, and hydrogen sulfide gases produced by bacteria and methanogens in the gastrointestinal tract over a two-hour testing period.
What Makes This Test Popular?
trio-smart is the most comprehensive SIBO breath test because it is the only test capable of measuring hydrogen sulfide gas levels. trio-smart offers both glucose and lactulose versions of the test.
When Should You Consider This Test?
The trio-smart test should be ordered for patients you are interested in assessing for hydrogen-SIBO, hydrogen sulfide-SIBO, and IMO. Patients unable to perform the lactulose breath test due to allergy can take the glucose breath test.
SIBO/IMO Test from Commonwealth Diagnostics International
What Does This Test Measure?
Commonwealth Diagnostics International (CDI) offers a glucose and a lactulose SIBO/IMO breath test. Both tests measure hydrogen and methane gas levels over a 2-hour and 15-minute time period.
What Makes This Test Popular?
Ordering physicians can order either a glucose or lactulose breath test, depending on their testing preferences and needs. Given the test duration, the lactulose breath test can assess for IMO in the beginning portion of the large intestine. CDI's SIBO breath tests are the least expensive SIBO testing option offered through Rupa Health.
When Should You Consider This Test?
If cost is an inhibiting factor for a patient, CDI's breath tests are good SIBO testing options for diagnosing hydrogen-SIBO and IMO. The SIBO/IMO glucose breath test can be ordered for patients with lactulose allergy.
Summary
SIBO breath tests act as convenient at-home testing aids to diagnose small intestinal bacterial overgrowth and intestinal methanogen overgrowth. Depending on your clinical needs, various breath tests may serve you better than others. SIBO breath tests primarily differ between the testing period's duration and the substrate included in the test kit. All SIBO breath tests measure hydrogen and methane gas levels derived from intestinal bacteria and methanogens. The trio-smart breath test is the only test that measures hydrogen sulfide gas levels. A comparison table for all SIBO breath tests available to order through Rupa Health can be viewed here.
Lab Tests in This Article
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References
1. Rezaie, A., Buresi, M., Lembo, A., et al. (2017). Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. The American Journal of Gastroenterology, 112(5), 775–784. https://doi.org/10.1038/ajg.2017.46
2. Breath Testing. Trio-smart. https://www.triosmartbreath.com/breathtesting
3. Rao, S.S., & Bhagatwala, J. (2019). Small Intestinal Bacterial Overgrowth. Clinical and Translational Gastroenterology, 10(10):p e00078. https://doi.org/10.14309/ctg.0000000000000078
4. Takakura, W., & Pimentel, M. (2020). Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome – An Update. Frontiers in Psychiatry, 11. https://doi.org/10.3389/fpsyt.2020.00664
