Background: Functional integrity as an aspect of the mucosal barrier function of the small bowel can be estimated by the intestinal permeability for macromolecules. In the first part of this paper, an overview of intestinal permeability and its measurement is given.
Methods: In the second part of the paper our own experience with the Sugar Absorption Test using lactulose and mannitol to assess mucosal barrier function of gastric, small and large bowel, respectively, is described.
Results and conclusions: The Sugar Absorption Test is not recommended as a predictor of NSAID-related upper gastrointestinal damage nor as a marker of disease activity in inflammatory bowel diseases. The Sugar Absorption Test is very useful in screening for small intestinal disease, in assessing the response to treatment, and in predicting the prognosis, especially in coeliac disease. In our opinion, the D-xylose test is obsolete.