Comparison between the Lactulose/Mannitol and ⁵¹Cr-Ethylenediaminetetraacetic Acid/¹⁴C-Mannitol Methods for Intestinal Permeability Frequency Distribution Pattern and Variability of Markers and Marker Ratios in Healthy Subjects

Abstract

Urinary excretion of lactulose and mannitol, determined by gas-liquid chromatography, was compared with that of ⁵¹Cr-ethylenediaminetetraacetic acid (EDTA) and ¹⁴C-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 ⁵¹Cr-EDTA (markers of paracellular permeability) were skewly distributed, as were the lactulose to mannitol and ⁵¹Cr-EDTA to ¹⁴C-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 ⁵¹Cr-EDTA excretion (p < 0.01) and between mannitol and ¹⁴C-mannitol excretion (p < 0.001) but not between the lactulose to mannitol and ⁵¹Cr-EDTA to ¹⁴C-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.

Key Words:

• ¹⁴C-mannitol
• ⁵¹Cr-ethylenediaminetetraacetic acid
• intestinal absorption
• intestinal permeability
• lactulose
• mannitol