In vitro determination of small intestinal permeability: demonstration of a persistent defect in patients with coeliac disease.

Previous methods for measuring intestinal permeability involve the urinary measurements of various poorly digested sugar or inert poly(ethylene glycol) polymers after their oral administration. The results reflect a variety of gastrointestinal parameters including transit time, mucosal surface area and transfer, mesenteric blood and/or lymphatic flow and renal function, as well as mucosal permeability. A new in vitro method for direct measurements of mucosal permeability to three probes is described and permeability is shown to be inversely related to the molecular weight of the probe molecule. Using this technique, a persistent increase in mucosal permeability to certain probes (molecular weight less than 1500 daltons) has been shown in patients with coeliac disease in whom treatment by strict gluten withdrawal has been accompanied by restoration of intestinal histological normality. It is suggested that this finding represents a primary defect in this syndrome.