title: 1H NMR spectroscopic method for diagnosis of malabsorption syndrome: a pilot study.
abstract: 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 (1)H 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<or=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>or=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.
authors.affiliation: Centre of Biomedical Magnetic Resonance, Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Raebareli Road, Lucknow 226 014, India.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Bala
authors.forename: G A
authors.initials: GA
authors.lastname: Nagana Gowda
authors.forename: U C
authors.initials: UC
authors.lastname: Ghoshal
authors.forename: A
authors.initials: A
authors.lastname: Misra
authors.forename: M
authors.initials: M
authors.lastname: Bhandari
authors.forename: C L
authors.initials: CL
authors.lastname: Khetrapal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003124:Colorimetry; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008286:Malabsorption Syndromes / Q000175:diagnosis* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016482:Urinalysis / Q000379:methods; D014994:Xylose / Q000652:urine*
chemical_list: D011522:Protons; D014994:Xylose