1H NMR spectroscopic method for diagnosis of malabsorption syndrome:: a pilot study

Despite its well-documented limitations, colorimetry has been commonly used for the D-xylose test in the diagnosis of malabsorption syndrome (MAS). With a possibility of overcoming its limitations, the use of H-1 NMR spectroscopy for D-xylose test is explored herein. Urine samples from 35 adults with suspected MAS were obtained before and after oral ingestion of D-xylose. The diagnosis of MAS was based on fecal fat (72 h excretion using Van de Kamer's technique, normal <7 g/24 h and/or Sudan III stain of spot stool specimen, normal less than or equal to 10 droplets/high power field) and/or endoscopic duodenal biopsy. Urinary excretion Of D-xylose over 5 h after consumption of 5 g D-xylose, using both colorimetry and NMR was compared (normal greater than or equal to 1 g/5 g/5 h). In vitro experiments on the standard specimens of D-xylose were also performed independently using both methods. Colorimetry showed a lower value for the quantity of D-xylose excreted in urine than NMR [median 0.73 (0.17-1.89 g) vs 1.37 (0.17-3.23 g), respectively; p < 0.0001, Wilcoxon's signed ranks test]. Colorimetry and NMR correctly diagnosed 11/12 and 10/12 (p = N.S.) patients with MAS and 14/23 and 20/23 (p < 0.05) without MAS, respectively. Sensitivity and specificity of colorimetry and NMR were 91.6 and 60.7% vs 83.3 and 86.9%, respectively. In in vitro experiments, the values obtained for standard xylose using NMR showed a maximum error of 7%, whereas the colorimetric method showed 20%. The NMR method is simple and may be more accurate for the D-xylose absorption test. Colorimetry was found to be inferior as compared with NMR due to its low specificity. Copyright (C) 2004 John Wiley Sons, Ltd.