Neurogastroenterol Motil. 2009 Jul 10. [Epub ahead of print]
Understanding measurements of intestinal permeability in healthy humans with urine lactulose and mannitol excretion.
Camilleri M, Nadeau A, Lamsam J, Linker Nord S, Ryks M, Burton D, Sweetser S, Zinsmeister AR, Singh R. From the Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER) Group, Mayo Clinic, Rochester, MN, USA.
Our aim was to understand the information from differential two-sugar excretion (2-SE) in measuring intestinal permeability. In a crossover study in 12 healthy volunteers, we compared urinary excretion ratios of lactulose (L) to mannitol [(M) LMR] after ingestion in liquid formulation (LF) or in delayed-release, methacrylate-coated capsules (CAP). Both formulations were radiolabelled. Urine was collected every 2 h from 0 to 8 h, and from 8 to 24 h. Two hours after LF, gastric residual was 15.9 +/- 6.2% (SEM), and the percentage in colon was 49.6 +/- 7.8%; in 11/12 participants, liquid had entered colon within 2 h. Average CAP arrival time in colon was 5.16 +/- 0.46 h (mode 6 h). After LF, mannitol was extensively absorbed in the first 8 h; lactulose absorption was low thoughout the 24 h. After the LF, the LMR (geometric mean, 95% CI per h) in the 0-2 h urine was [0.08 (0.05, 0.11)], which was lower than in 8-24 h urine [0.32 (0.16, 0.46); P < 0.05]. Urine LMRs at 8-24 h were similar after LF or CAP. We concluded that, after LF, sugar excretion in 0-2 h urine may reflect both SI and colon permeability. Colonic permeability is reflected by urine sugar excretion between 6 and 24 h. CAP delivery reduces mannitol excreted at 0-6 h, compared with LF. The 0-5 or 6 h 2-SE urine likely reflects both SI and colon permeability; the higher LMR in the 8-24 h urine relative to 0-2 h urine should be interpreted with caution and does not mean that colon is more permeable than SI.
PMID: 19614866 [PubMed - as supplied by publisher]