Rapid and simultaneous quantification of rhamnose, mannitol, and lactulose in urine by HPLC for estimating intestinal permeability in pediatric practice

Determination of intestinal permeability by measuring nonmetabolized sugars has been used to assess the integrity of intestinal mucosa. We have developed and validated a modified HPLC method for determining the concentration of L-rhamnose, mannitol, and lactulose in urine, using an amine-modified silica column and refractive index detection. Probe sugars are simultaneously resolved within 18 min. The calibration curve for each sugar is linear to 20 mmol/L. The minimum detectable concentration of lactulose is 0.05 mmol/L. Recovery of probe sugars is between 99.3% and 105.1%. Overall precision (CV) of estimation of probe sugars ranges from 4.2% to 6.5%. In 14 urine samples from healthy children who ingested the test solution containing 1 g of L-rhamnose, 1 g of mannitol, and 5 g of lactulose, the 5-h urinary excretion ratios of lactulose/rhamnose and lactulose/mannitol were 0.047 +/- 0.018 and 0.021 +/- 0.010 (mean +/- SD), respectively. This method presents a rapid, convenient, and practical technique for determining intestinal permeability in clinical pediatric practice.