Sensitivity of a hyperosmolar or "low"-osmolar test solution for sugar absorption in recognizing small intestinal mucosal damage in coeliac disease

Reliability of differential sugar absorption tests is hampered by a lack of standardization of the content and osmolarity of the test solutions. We ev aluated the effect of osmolarity of the test solution of the sugar absorpti on test on the 5 hour urine excretion of orally administered lactulose and mannitol. A group of 28 controls and 14 coeliacs, with villous atrophy grad e II to IV ingested a hyperosmolar sugar absorption test solution and a "lo w"-osmolar solution, respectively: After an overnight fast, each subject in gested hyperosmolar sugar absorption test solution (2 g mannitol, 5 g lactu lose and 40 g sucrose/100 ml (around 1560 mmol/l)). After two days, this pr ocedure was repeated with low-osmolar solution (2 g mannitol and 5 g lactul ose/100 ml (around 375 mmol/l)). The influence of the sequence of the tests on the results had previously been excluded. All urine from the 5 h-period following ingestion of the test solution was collected. To calculate the l ow-osmolar solution ratio, samples were analysed for lactulose and mannitol concentrations by gas chromatography. The sensitivity of hyperosmolar SAT solution and low-osmolar solution for the detection of mucosal abnormalitie s in coeliacs was 64% and 43%, respectively. In conclusion, a hyperosmolar solution discriminates better between normal and damaged mucosa of the smal l bowel such as villous atrophy due to a relative increase in permeability for lactulose.