Lactulose-rhamnose intestinal permeability in children with cystic fibrosis

The lactulose-rhamnose intestinal permeability test was performed in 10 cystic fibrosis (CF) children. Urine was collected for 5 h after oral intake of the test solution. A single thin-layer chromatography followed by densitometry was used for the measurement of lactulose and rhamnose concentrations in the urine specimens. The excretion of each molecule was expressed as the percentage of the orally administered dose excreted and the lactulose-rhamnose ratio was the ratio of the percentage quantities of each probe molecule excreted. The mean lactulose-rhamnose excretion ratio in CF patients and controls was 0.16 and 0.038, respectively (p less than 0.001). The mean 5-h lactulose excretion was 2% and 0.28% in CF patients and control subjects, respectively (p less than 0.001). The mean 5-h rhamnose excretion was 12.8% and 7.6% in CF patients and control subjects (p less than 0.05). We conclude that CF patients have an increased intestinal permeability to lactulose and rhamnose. Further studies are needed in order to elucidate the mechanisms involved as well as the eventual nutritional implications.