Association Between Symptoms Of Irritable Bowel Syndrome And Methane And Hydrogen On Lactulose Breath Test

Background: Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder characterized by bowel habit changes and abdominal pain or discomfort relieved by defecation in the absence of organic disease, symptoms can persist or intermittent attacks. The pathophysiology of IBS is multifactorial and unclear. Recently, small intestinal bacterial overgrowth(SIBO) has been advocated as a pathogenetic factor of IBS, and widely involved in the pathological physiological process of IBS. Lactulose breath test (LBT) is one of the non-invasive tests and can detect hydrogen and methane gas produced by bacterial fermentation of unabsorbed intestinal lactulose and excreted in the breath. Patients of SIBO in LBT would produce hydrogen and methane, and IBS patients are widespread gas related symptoms such as abdominal distension, bloating, abdominal pain, gas generation and the size of gas may be the important cause of the symptoms.Object: This study aims to by measuring the IBS patients with lactulose hydrogen and methane production in the breath test, collection of patients with gastrointestinal symptoms severity score, comparison of lactulose breath test positive results and the relationship between the gas and in patients with IBS symptoms.Methods:Choose in June2013to March2014to our digestive internal medicine outpatient and hospitalization, conform to the Roman III diagnostic criteria of43patients with IBS,16cases of health volunteers. All the subjects accepted lactulose breath test, and IBS patients were asked to fill out a symptom questionnaire for evaluating the severity of their lower GI symptoms. An LBT result was considered positive when the hydrogen gas level exceeded20ppm at baseline or showed an increase of20ppm over baseline within90min; methane gas level exceeded10ppm at baseline or showed an increase of10ppm over baseline within90min. Cumulative hydrogen or methane production was quantified from the graph by calculating the area under the curve (AUC) of hydrogen or methane concentration over time. Compare the IBS patients and the control group LBT positive rate, compare each subtype of IBS LBT positive rate and symptom scores. IBS patients can be divided into LBT(H2)+group, fasting LBT(H2)+group, LBT(CH4)+group and LBT negative group according to the results of the breath. Records of the patient’s symptom scores, SIBO positive rate, gas concentration and gas volume. Compare IBS patients group and the control group by the positive rate, expiratory hydrogen density and gas production, into a step confirmed in LBT test of gas production and the relationship between IBS symptoms.Result:1. The IBS patients had a higher LBT positivity than health controls(P=0.09), the female patients with IBS had a higher LBT positivity than male patients(P=0.017), The LBT (CH4)+group was significantly older than the LBT(-) group;2.H2volume was significantly greater in the LBT(+) IBS group than in the LBT(-) IBS group(P<0.001), the IBS-C subgroup showed significantly greater CH4volume as compared to the IBS-D subgroup (P=0.045), intestinal gas volume was significantly greater in the LBT(+) group than in the LBT negative group(P=0.02);3.Mean symptom severity scores of bloating(P=0.02) and constipation(P=0.01) in LBT(+) IBS group were higher than LBT(-) IBS group, mean symptom severity scores of flatulence(P=0.009) and bloating(P=0.0036) in LBT(H2)+group were higher than LBT(H2)-group, mean symptom severity scores of constipation in LBT(CH4)+group were higher than LBT(CH4)-group, mean symptom severity scores of abdominal pain(P=0.04), flatulence(P=0.03) and bloating(P=0.001) in fasting LBT(H2)+group were higher than non-fasting LBT(H2)+group;4. There was a correlation between symptom severity scores for bloating (r=0.323, P=0.035), abdominal pain (r=0.447, P＜0.001) and constipation(r=0.326, P=0.033) and the AUCs of total gas volume.Conclusion: The IBS patients had a higher LBT positivity than health controls, the onset of IBS and SIBO has certain correlation. H2and CH4generated in LBT is associated with specific symptoms of patients with IBS. Gas volume is associated with the symptoms of IBS patients. H2and CH4generated in LBT can be used to predict patients with IBS symptoms.