Abnormal intestinal permeability to sugars in villous atrophy.

Intestinal permeability to a monosaccharide and a disaccharide was compared by simultaneous measurement of the urinary excretion of L-rhamnose and lactulose after oral ingestion of an hypertonic solution containing both sugars. Urine samples were analysed for sugar content by quantitative thin-layer or paper chromatography. Results in thirteen patients with untreated villous atrophy were compared with those in twelve healthy volunteers. Urinary L-rhamnose excretion was significantly decreased (-40%, p less than 0.02) in patients with villous atrophy, whereas lactulose excretion was paradoxically and significantly increased (+345%, p less than 0.01). The median value of the lactulose/L-rhamnose urinary excretion ratio was sevenfold higher in the patients with villous atrophy; there was no overlap of values for patients and volunteers (p less than 0.01). It is postulated that reduced L-rhamnose urinary excretion in untreated villous atrophy is due to a decreased absorptive area in the small bowel, whereas increased lactulose excretion indicates leakiness of the abnormal mucosa to larger polar molecules.