Objective: Abnormal lactulose breath test has been found in patients with irritable bowel syndrome. However, there are no generally acknowledged criteria for interpretation of lactulose breath test, and little data describing the outcome of this test in the normal population.
Material and methods: We compared a group of patients with irritable bowel syndrome (n=21) meeting the Rome II criteria with a group of healthy controls (n=25). Lactulose breath test was performed using a 10 g lactulose challenge, and an abnormal test was defined as a rise >20 ppm within 90 min of either hydrogen, methane or hydrogen and methane combined. The results were analyzed to find the most useful time point to differentiate patients from controls. A questionnaire was used prior to, during and after the test to assess symptoms.
Results: Twenty-four percent of patients and 44% of controls had an abnormal breath test using hydrogen only, while with hydrogen and methane combined 29% of patients and 44% of controls had abnormal tests (p=ns). There was no time point that was eligible to differentiate patients from controls. More patients than controls reported of symptoms in relation to the test (p<0,05), but there was no clear relation between outcome of the test and symptom report.
Interpretation: Our study shows no value of lactulose breath test in diagnosing irritable bowel syndrome.