From the Guidelines
The lactulose breath test is a recommended diagnostic tool for detecting small intestinal bacterial overgrowth (SIBO) in patients with inflammatory bowel disease (IBD), despite its limitations, as it is non-invasive and can help guide treatment decisions 1. The test involves collecting breath samples at regular intervals after lactulose ingestion, and elevated levels of hydrogen and/or methane gases appearing earlier than expected suggest SIBO. Some key points to consider when using the lactulose breath test include:
- Patients should fast for 12 hours before the test and avoid certain foods for 24 hours prior 1
- Medications that affect gut motility or bacterial populations should be discontinued for varying periods before testing, typically 2-4 weeks for antibiotics 1
- The test has limitations, including potential false positives and negatives due to factors like rapid or delayed transit time 1
- Recent consensus guidelines suggest using hydrogen and methane-based breath testing for SIBO using glucose or lactulose substrates until validated gold standards for testing are established 1
- The sensitivity and specificity of lactulose hydrogen breath testing have ranged from 31 to 68% and 44 to 100%, respectively 1
- Some have suggested that lactulose breath testing be avoided due to effects on small bowel transit and concerns of its sensitivity and specificity, but it remains a useful diagnostic tool in certain cases 1
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Lactulose Breath Test Overview
- The lactulose breath test (LBT) is a noninvasive test used to diagnose small intestinal bacterial overgrowth (SIBO) 2, 3, 4, 5, 6.
- SIBO is a condition characterized by an excess of bacteria in the small intestine, leading to symptoms such as bloating, abdominal distension, diarrhea, and weight loss 2.
Diagnostic Criteria and Limitations
- The LBT measures the production of hydrogen and methane in the breath after ingestion of lactulose, a non-absorbable sugar 4, 5, 6.
- However, the validity of the LBT has been questioned due to its potential for false positive results and inability to discriminate between patients with SIBO and those without 3, 5, 6.
- Studies have suggested that the glucose breath test (GBT) may be a more accurate and reliable test for diagnosing SIBO 3, 5.
Comparison with Glucose Breath Test
- A study comparing LBT and GBT found that LBT had a lower specificity and positive predictive value for diagnosing SIBO in patients with irritable bowel syndrome (IBS) 5.
- Another study found that LBT was not useful in discriminating between IBS patients and controls, while GBT was able to detect SIBO more accurately 6.