Combined LDI/SAT test to evaluate intestinal lactose digestion and mucosa permeability

H. A. Koetse, D. Klaassen, A. R. H. van der Molen, H. Elzinga, K. Bijsterveld, R. Boverhof, F. Stellaard*

*Corresponding author for this work

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    Background Intestinal mucosal damage causes impaired digestive capacity and increased mucosal permeability. Quantification of damage can be used to improve treatment options. Currently, the Lactose Digestion Index (LDI) and the Sugar Absorption Test (SAT) are used for evaluation. The investigation studied whether both tests could be combined to provide a useful multifunctional test and whether measurements in blood (LDI) could be replaced by measurements in urine.

    Materials and Methods The LDI (25 g C-13-lactose, 0.5 g H-2-glucose), the SAT (5 g lactulose, 1 g L-rhamnose) and the LDI/SAT combination test were performed in seven lactose-digesting and eight lactose-maldigesting adults. Plasma glucose C-13-enrichment was determined by gas-chromatography/combustion/isotope ratio mass-spectrometry (GC/C/IRMS), H-2 enrichment determined by gas-chromatography/mass-spectrometry (GC/MS) and urinary sugars by gas-chromatography (GC).

    Results The results of the separate LDI test were not different from those of the LDI/SAT in the lactose-digester group (0.82 +/- 0.06 vs. 0.81 +/- 0.09), nor in the lactose-maldigester group (0.36 +/- 0.12 vs. 0.35 +/- 0.06). A significant correlation was found between the 10-h urinary-lactose/lactulose ratio and the LDI (R-2 = 0.71, P <0.01). There were no differences in the lactulose/L-rhamnose ratio between lactose-digesters and lactose-maldigesters using both the SAT and LDI/SAT tests.

    Conclusion The LDI/SAT test is a reliable method of measuring digestion and permeability simultaneously. The 10-h period urinary lactose/lactulose excretion ratio following lactose consumption reflects lactose digestive capacity.

    Original languageEnglish
    Pages (from-to)730-736
    Number of pages7
    JournalEuropean Journal of Clinical Investigation
    Issue number10
    Publication statusPublished - Oct-2006


    • intestinal function
    • lactose digestion
    • mucosal permeability
    • stable isotopes
    • urinary differential disaccharide excretion
    • CANCER
    • DAMAGE

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