Intestinal permeability as a measure of small intestinal mucosal integrity: correlation with jejunal biopsy

Abstract

The permeability of the small intestine was measured and jejuna] biopsy performed in 39 children with gastrointestinal disorders. Intestinal permeability was measured using orally administered mannitol and lactulose as probe molecules in an isotonic solution (274 mOs/l), and the results were expressed as the ratio of the urinary excretion of the two sugars over 5 h. Urine samples were analysed for mannitol and lactulose content by high performance liquid chromatography. Children with small intestinal mucosal damage, irrespective of the cause, had a significantly lower (P < 0.001) mannitol excretion (mean recovery 1.21% of ingested dose) than those with a normal mucosa (mean recovery 5.3%), while lactulose excretion did not differ (P > 0.05). The mean value of the lactulose:mannitol urinary excretion ratios was significantly higher (P < 0.001) in subjects with an abnormal mucosa (0.98) compared to those with a normal mucosa (0.2). Using the mean plus two standard deviations of the normal musosa group to define the upper limit of normal, all lactulose: mannitol excretion ratios from the abnormal mucosa group were above this limit. The results of this study show that the sugar permeability test is a sensitive, non-invasive screening test for jejunal mucosal damage in children and shows good correlation with jejunal biopsy results.