COMPARISON BETWEEN THE LACTULOSE MANNITOL AND CR-51 ETHYLENEDIAMINETETRAACETIC ACID C-14 MANNITOL METHODS FOR INTESTINAL PERMEABILITY - FREQUENCY-DISTRIBUTION PATTERN AND VARIABILITY OF MARKERS AND MARKER RATIOS IN HEALTHY-SUBJECTS

Urinary excretion of lactulose and mannitol, determined by gas-liquid chromatography, was compared with that of Cr-51-ethylenediaminetetraacetic acid (EDTA) and C-14-mannitol for measurement of intestinal permeability in 28 healthy humans. The 0- to 6-h excretion values for unlabelled and labelled mannitol (marker of transcellular permeability) were normally distributed, whereas excretion values for lactulose and Cr-51-EDTA (markers of paracellular permeability) were skewly distributed, as were the lactulose to mannitol and Cr-51-EDTA to C-14-mannitol ratios. Excretion of the transcellular markers but not of the paracellular markers was significantly correlated to urinary volume; correction for urinary volume resulted in decreased test variability. Significant correlation was found between lactulose and Cr-51-EDTA excretion (p < 0.01) and between mannitol and C-14-mannitol excretion (p < 0.001) but not between the lactulose to mannitol and Cr-51-EDTA to C-14-mannitol ratios (p = 0.11). Inter- and intra-individual test variability was greater for each chemically determined marker than for the corresponding isotope-labelled marker. Similarly, variability was greater for each paracellular marker than for the corresponding transcellular marker and for each paracellular/transcellular marker ratio than for the transcellular marker alone. Variability of mannitol excretion was increased by the frequent presence of food-derived mannitol in the urine.