The sensitivity of the lactulose/rhamnose gut permeability test

Abstract

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.

Effects of pre- and post-absorptive factors on the lactulose/rhamnose gut permeability test

“…In our recent study [4] we demonstrated that the dose-absorption kinetics of lactulose and rhamnose follow a non-linear function ; if the permeability is increased, the lactulose\rhamnose ratio is higher if larger quantities of the molecules are applied. Although it is assumed that pre-and post-absorptive factors do not influence the outcome of the lactulose\rhamnose permeability test, the recovery data from the previous study [4] demonstrated that, if intestinal permeability is increased, the administration of a higher dose of lactulose and rhamnose results in unchanged lactulose recovery but in decreased rhamnose recovery.…”

“…Recently we demonstrated that, under conditions of increased intestinal permeability, the outcome of the lactulose\rhamnose test is influenced by the dose of lactulose\rhamnose administered [4]. This suggests a possible involvement of pre-and\or post-absorptive factors in addition to the process of intestinal permeation if the permeability is increased, which will determine the outcome of the test.…”

Effects of oral adenosine 5'-triphosphate and adenosine in enteric-coated capsules on indomethacin-induced permeability changes in the human small intestine: a randomized cross-over study

“…This test is based on the comparison of intestinal permeation of molecules of different sizes. The urinary L/R excretion ratio is considered to be an accurate parameter of small intestinal permeability [24]. Lactulose and L-rhamnose in collected urine samples were determined by fluorescent detection high-pressure liquid chromatography (HPLC).…”

“…In this randomized cross-over study, fasting subjects received two subsequent indomethacin dosages (75 and 50 mg) concomitant with administration of ATP or placebo directly into the upper small intestine via a naso-intestinal tube. Intestinal permeability was measured by the lactulose/rhamnose (L/R) sugar absorption test, which is a widely used and sensitive permeability measure of the small intestine [24]. Results showed that indomethacin induced an approximately two-fold increase in median urinary L/R excretion ratio relative to the basal L/R ratio in the control condition ( i.e .…”

The effect of aspirin and smoking on urinary excretion profiles of lactulose and mannitol in young women: toward a dynamic, aspirin augmented, test of gut mucosal permeability

“…The study was thus a pilot in this regard. Twenty participants successfully completed the experimental regime, a number that was broadly in line with the number of individuals per treatment in previous studies 13,16,34,35 …”