BackgroundThe lactulose/rhamnose (L/R) intestinal permeability test is widely used. However, different quantities and proportions of lactulose and rhamnose are used. The aim of this study was to determine whether a low dosage of lactulose is able to discriminate between normal and increased permeability.
Materials and methodsTwo groups of 10 healthy subjects were studied. In group 1, three different iso-osmolar test solutions were administered on 3 days. The solutions consisted of 10 g of L with 1 g of R, 5 g of L with 0·5 g of R and 1 g of L with 0·1 g of R in 65 mL of water. Group 2 ingested these solutions 1 h after ingestion of 750 mg of chenodeoxycholeic acid (CDCA), which is known to increase permeability. The urinary L/R ratio was determined using high-performance liquid chromatography. Data are presented as medians (range).
ResultsIn group 1, no differences were observed between the three solutions. In Group 2, there was a significant difference (P ¼ 0·045) between the three solutions. The L/R ratios were 0·0079 (0·0024-0·0152) (1L to 0·1R), 0·0138 (0·0066-0·0192) (5L to 0·5R) and 0·0144 (0·0074-0·0374) (10L to 1R). The L/R ratio differed significantly between Groups 1 and 2 (P < 0·001) using the 5L to 0·5R and 10L to 1R solutions respectively.Conclusion If the permeability is increased, the urinary L/R ratio depends on the quantity of lactulose and rhamnose administered in equal proportion. 5L to 0·5R is sufficient to discriminate between a normal and a moderately increased permeability.
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