The sensitivity of the lactulose/rhamnose gut permeability test.
BACKGROUND
The 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.


METHODS
Two 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).


RESULTS
In group 1, no differences were observed between the three solutions. In Group 2, there was a significant difference (P = 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.


CONCLUSIONS
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.
van Nieuwenhoven
M A
MA
Department of Human Biology, Maastricht University, The Netherlands. M.vanNieuwenhoven@HB.UNIMAAS.nl
Geerling
B J
BJ
Deutz
N E
NE
Brouns
F
F
Brummer
R J
RJ
D000293:Adolescent; D000328:Adult; D002635:Chenodeoxycholic Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology*; D007792:Lactulose / Q000378:metabolism* / Q000652:urine; D008297:Male; D008722:Methods; D010539:Permeability; D012210:Rhamnose / Q000378:metabolism* / Q000652:urine; D012680:Sensitivity and Specificity
D002635:Chenodeoxycholic Acid; D007792:Lactulose; D012210:Rhamnose