BACKGROUND: The phloroglucinol assay is the current method for d-xylose determination in urine/plasma/serum. However, its sensitivity is limited when low amounts of d-xylose are to be measured, such as in the noninvasive evaluation of intestinal lactase with 4-galactosylxylose (gaxilose). An improved assay was therefore needed. METHODS: We developed and validated a modified version of the phloroglucinol-based assay for quantification of d-xylose in urine/serum samples. A method for gaxilose determination by gas chromatography (GC) was also optimized. RESULTS: Linearity ranged from 0.125 to 5.0 mg/l (5-200 mg/l in original sample). Accuracy at LOQ (0.125 mg/l) was 0.97/2.49% in spiked urine/serum; for other quality controls (QC), it was <1.27%. Intra- and interassay precision at LOQ were 6.02% and 6.45% for urine, and 8.86% and 10.00%, respectively, for serum; for other QC, precision was <2.15%. Linearity of gaxilose determination by GC was 3.90-195.17 for urine and 9.75-195.17 mg/l for serum with acceptable sensitivity and reproducibility. The method proved adequate for the d-xylose determination in healthy and hypolactasic subjects after oral administration of gaxilose. CONCLUSIONS: The modified method provides high sensitivity and robustness for d-xylose quantification in urine/serum for routine clinical use especially in the noninvasive diagnosis of intestinal lactase deficiency with the gaxilose test.
BACKGROUND: The phloroglucinol assay is the current method for d-xylose determination in urine/plasma/serum. However, its sensitivity is limited when low amounts of d-xylose are to be measured, such as in the noninvasive evaluation of intestinal lactase with 4-galactosylxylose (gaxilose). An improved assay was therefore needed. METHODS: We developed and validated a modified version of the phloroglucinol-based assay for quantification of d-xylose in urine/serum samples. A method for gaxilose determination by gas chromatography (GC) was also optimized. RESULTS: Linearity ranged from 0.125 to 5.0 mg/l (5-200 mg/l in original sample). Accuracy at LOQ (0.125 mg/l) was 0.97/2.49% in spiked urine/serum; for other quality controls (QC), it was <1.27%. Intra- and interassay precision at LOQ were 6.02% and 6.45% for urine, and 8.86% and 10.00%, respectively, for serum; for other QC, precision was <2.15%. Linearity of gaxilose determination by GC was 3.90-195.17 for urine and 9.75-195.17 mg/l for serum with acceptable sensitivity and reproducibility. The method proved adequate for the d-xylose determination in healthy and hypolactasic subjects after oral administration of gaxilose. CONCLUSIONS: The modified method provides high sensitivity and robustness for d-xylose quantification in urine/serum for routine clinical use especially in the noninvasive diagnosis of intestinal lactase deficiency with the gaxilose test.
Authors: J J Aragón; A Fernández-Mayoralas; J Jiménez-Barbero; M Martín-Lomas; A Rivera-Sagredo; D Villanueva Journal: Clin Chim Acta Date: 1992-09-30 Impact factor: 3.786
Authors: Carmen Hermida; Guillermo Corrales; Oscar H Martínez-Costa; Alfonso Fernández-Mayoralas; Juan J Aragón Journal: Clin Chem Date: 2005-12-29 Impact factor: 8.327
Authors: J J Aragón; F J Cañada; A Fernández-Mayoralas; R López; M Martín-Lomas; D Villanueva Journal: Carbohydr Res Date: 1996-09-02 Impact factor: 2.104
Authors: Carmen Hermida; Guillermo Corrales; Francisco J Cañada; Juan J Aragón; Alfonso Fernández-Mayoralas Journal: Bioorg Med Chem Date: 2007-05-06 Impact factor: 3.641
Authors: Israel Sánchez-Moreno; Carmen Monsalve-Hernando; Ana Godino; Luis Illa; María Jesús Gaspar; Guillermo Manuel Muñoz; Ana Díaz; José Luis Martín; Eduardo García-Junceda; Alfonso Fernández-Mayoralas; Carmen Hermida Journal: Biomed Res Int Date: 2017-09-24 Impact factor: 3.411
Authors: Carmen Monsalve-Hernando; Laura Crespo; Blanca Ferreiro; Verónica Martín; Xavier Aldeguer; Verónica Opio; Pedro Luis Fernández-Gil; María Jesús Gaspar; Eduardo Romero; Carmen Lara; Cecilio Santander; Leyanira Torrealba; Theodora Savescu; Carmen Hermida Journal: Medicine (Baltimore) Date: 2018-11 Impact factor: 1.817