Assessment of intestinal permeability using sugar probes: influence of urinary volume.

BACKGROUND: As the accuracy of the "Sugar Test" is currently debated, this study was conducted to focus on how urine volumes may impact the test results. METHODS: Fifty-five subjects, 23 healthy and 32 with Irritable Bowel Syndrome (IBS), were enrolled. Lactulose and D-mannitol dissolved in water were administered to all the participating subjects; the urine excreted was collected and the total urine volume was measured. The urine samples were analyzed by High Performance Liquid Chromatography (HPLC). The results were expressed as percentage of urine recovery of lactulose and D-mannitol and lactulose/D-mannitol ratio (LMR). RESULTS: All subjects were divided into two groups: subjects with urine volume < 500 mL and subjects with urine volume > or = 500 mL. Urine analysis showed that the mean LMR was significantly lower in subjects with urine volume > or = 500 mL than in subjects with urine volume < 500 mL (0.02 +/- 0.02 vs 0.04 +/- 0.04; p < 0.05). A significant increase in D-mannitol recovery was found to be associated with greater urine volumes (p < 0.001). CONCLUSIONS: The urine volume may influence urinary excretion of sugar probes. Intake of liquids should therefore be carefully monitored before and during the test and the volume of urine produced over the period of collection should be precisely measured.

Positive glucose breath testing is more prevalent in patients with IBS-like symptoms compared with controls of similar age and gender distribution.

BACKGROUND: Small intestinal bacterial overgrowth (SIBO) may mimic a functional disorder such as irritable bowel syndrome (IBS) or functional bloating (FB). In this study, we aimed to assess the utility of glucose breath test (GBT) in patients with the above conditions. METHODS: This study included 200 consecutive patients (130 with IBS and 70 with FB on the basis of Rome III criteria) and 70 controls with similar age and sex distribution. Patients and controls underwent 50 g GBT and a H2 peak of > or = 12 ppm was considered diagnostic of SIBO. Positive patients received rifaximin of 1200mg/day for 10 days and underwent a second GBT 1 month after the end of treatment. A symptom questionnaire was completed before and after therapy. RESULTS: GBT resulted to be altered in 21 out of 130 IBS patients and in 2 out of 70 FB patients with a significant difference of the former group compared with controls (3 out of 70, P=0.0137). Most IBS patients with a positive GBT complained of diarrhea. GBT showed an increased methane excretion in 26% of patients, who were equally distributed among different bowel pattern subgroups. Previous abdominal surgery was more frequently seen in GBT-positive patients (P=0.008). After antibiotic treatment, eradication of SIBO was achieved in 70% of patients, with a significant improvement of symptoms in eradicated patients compared with the not eradicated ones (P<0.001). CONCLUSIONS: GBT is useful to identify a subgroup of IBS-like patients, whose symptoms are owing to SIBO. Normalization of GBT after antibiotic therapy is associated with a significant improvement of symptoms. GBT does not offer any advantage in FB patients.