Increased intestinal permeability in patients with inflammatory bowel disease

Intestinal permeability can be measured by the sugar absorption test. This test is based on determining the ratio of the urinary excretion of a large and a small carbohydrate after oral administration. The aim of this study was to determine which combination of carbohydrates used in the test gives the highest correlation with disease activity in inflammatory bowel disease. 26 patients with Crohn's disease, 21 patients with ulcerative colitis and 27 healthy control subjects were included in the study. The patients with inflammatory bowel disease had either minimal or highly active disease or were in remission. Two disaccharides (lactulose: L, and cellobiose: C) and two smaller carbohydrates (rhamnose:R, and mannitol:M) were given orally and the urinary excretion was measured by high pressure liquid chromatography followed by pulsed amperometric electrochemical detection on a gold electrode. The ratios C/R, L/R, C/M and L/M were used as indicators for intestinal permeability. - There were no side effects of oral sugar administration. All patients tolerated the test well. Lactulose, rhamnose and cellobiose concentrations are easily be measured in the urine whereas mannitol measurement requires the use of an anion exchanger. This produced inconsistent results. Patients with Crohn's disease or with ulcerative colitis had increased permeability indices in comparison to healthy controls, even in remission. The L/R ratio gave a better differentiation between the healthy controls and patients with active disease than the other agents. Changes in disease activity are best reflected by use of cellobiose/rhamnose excretion quotient.