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 ≥500 mL. Urine analysis showed that the mean LMR was significantly lower in subjects with urine volume ≥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.