Background/aims: Measurement of lactulose excretion in urine following oral ingestion is used as a noninvasive method of assessing small intestinal permeability. The aim of this study was to determine the adult reference interval of urinary lactulose excretion following oral administration.
Methods: Thirty seven volunteers (mean age 37.3 +/- 15 years) with no history of gastrointestinal disease were recruited as study subjects. All subjects were fasted overnight (10 hours), emptied their bladders and then drank a 50-mL solution containing 15 mL of Duphalac (10 g lactulose) and 35 mL flavoured water. Urine was collected for six hours in a bottle. Comparisons were made for 37 samples.
Results: In adults, the mean urinary lactulose concentration was 0.58 +/- 0.39 mmol/L.
Conclusion: This study determined the adult reference range for lactulose excreted in the urine, using a sensitive quantitative assay based on hydrolysing lactulose and enzymatically assaying fructose, one of the component monosaccharides.