Department of Medical Biochemistry, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
Department of Child Health and Diseases, Metabolism and Nutrition Units, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
Clin Chim Acta. 2017 Jan;464:72-78. doi: 10.1016/j.cca.2016.11.015. Epub 2016 Nov 15.
Comprehensive analytical and diagnostic performance of urinary quantitative GAG analysis with dimethylmethylene blue (DMB) and the age-specific reference ranges were determined in Turkish population, which has a high incidence of MPSs. Precision, linearity, recovery and accuracy/trueness, limits, stability, and effect of interferents were tested according to CLSI guideline. Clinical performance was evaluated with ROC analyses including 45 MPS patients. Intra-day and inter-day precisions were <5% and <11% (CV), respectively. LoD was 9.12mg/L and LoQ was 23.3mg/L. The highest reference values for urinary GAG excretion were determined in an age-specific manner. In the 2-13years age cohort, a cut-off of 89.86mg/g creatinine resulted in 98.07% sensitivity and 93.33% specificity. Proteinuria and hematuria interfered with analysis in some instances. Neither leukocyturia nor pH changes affected the assay. Stability analysis indicated that freezing urine samples for transfer is unnecessary. Of the 45 MPS patient samples evaluated, only three tested negative including MPS II, IVA and VI. Despite limitations due to low levels of urinary GAG excretion in some cases, urinary GAG analysis with DMB with its technical simplicity, low cost, and precise quantitative results, is a valuable screening method, particularly in populations with a high rate of MPSs.
在具有较高黏多糖贮积症（MPS）发病率的土耳其人群中，我们确定了使用二甲亚甲基蓝（DMB）进行尿定量 GAG 分析的综合分析和诊断性能及其特定年龄的参考范围。根据 CLSI 指南，我们测试了精密度、线性、回收率和准确度/真实性、限界、稳定性以及干扰物的影响。通过 ROC 分析评估了临床性能，其中包括 45 名 MPS 患者。日内和日间精密度分别<5%和<11%（CV）。LoD 为 9.12mg/L，LoQ 为 23.3mg/L。以特定年龄的方式确定了尿 GAG 排泄的最高参考值。在 2-13 岁年龄组中，以 89.86mg/g 肌酐为截止值，可实现 98.07%的灵敏度和 93.33%的特异性。蛋白尿和血尿在某些情况下会干扰分析。白细胞尿或 pH 值变化均不会影响测定。稳定性分析表明，没有必要冷冻转移尿液样本。在所评估的 45 名 MPS 患者样本中，仅 3 例检测结果为阴性，包括 MPS II、IVA 和 VI。尽管由于某些情况下尿 GAG 排泄水平较低存在一些限制，但使用 DMB 进行尿 GAG 分析具有技术简单、成本低廉和精确的定量结果，是一种有价值的筛选方法，特别是在 MPS 发病率较高的人群中。
