The sensitivity of the lactulose/rhamnose gut permeability test

Background The lactulose/rhamnose (UR) intestinal permeability test is wide ly used. However, different quantities and proportions of lactulose and rha mnose are used. The aim of this study was to determine whether a low dosage of lactulose is able to discriminate between normal and increased permeabi lity. Materials and methods Two groups of 10 healthy subjects were studied. In gr oup 1, three different iso-osmolar test solutions were administered on 3 da ss. 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 thes e solutions 1 h after ingestion of 750 mg of chenodeoxycholeic acid (CDCA), which is known to increase permeability. The urinary L/R ratio was determi ned using high-performance liquid chromatography. Data are presented as med ians (range). Results In group 1, no differences were observed between the three solution s. In Group 2, there was a significant difference (P = 0.045) between the t hree solutions. The L/R ratios were 0.0079 (0.0024-0.0152) (1L to 0.1R), 0. 0138 (0.0056-0.0192) (5L to 0.5R) and 0.0144 (0.0074-0.0374) (10L to 1R). T he L/R ratio differed significantly between Groups 1 and 2 (P < 0.001) usin g the 5L to 0.5R and 10L to 1R solutions respectively. Conclusion If the permeability is increased, the urinary UR ratio depends o n 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.