RESUMO
We evaluated the urinary glucose tetrasaccharide (Glc4) assay using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The calibration curve was linear over a range of 5-500 micromol/L. Performance parameters such as intra- and inter-day imprecision CVs were 6.52-14.6% and 11.5-13.2%, respectively. The mean concentrations of urinary Glc4 in 27 normal controls and 3 pseudodeficiency patients were 1.5 and 12.1 mmol/mol creatinine, respectively. Urinary Glc4 concentration in a patient with Pompe disease was 171.3 mmol/mol creatinine, which decreased to 130.9 mmol/mol following enzyme replacement therapy. Based on our results, we suggest that the urinary Glc4 assay using UPLC-MS/MS can be a reliable diagnostic tool for identification of patients with Pompe disease.