Roth Heinz Jürgen, Schmidt-Gayk Heinrich, Weber Holger, Niederau Christoph
Limbach Laboratory, Department of Endocrinology and Oncology, Im Breitspiel 15, 69126 Heidelberg, Germany.
Ann Clin Biochem. 2008 Mar;45(Pt 2):153-9. doi: 10.1258/acb.2007.007091.
The most reliable assessment of vitamin D status is measurement of plasma 25-hydroxyvitamin D (25[OH]D) concentration. High variability in 25(OH)D measurements due to utilized test and assay technologies and the lack of standardization against reference materials and reference method often confounds proper assessment of vitamin D status.
We evaluated the accuracy of six routinely available methodologies: high-performance liquid chromatography (HPLC), the IDS-radioimmunoassay (IDS-RIA) and enzyme immunoassay (IDS-EIA), the Nichols Advantage automated protein-binding assay (Advantage), two versions of the DiaSorin automated immunoassay (Liaison 1 and Liaison 2)--and one prototype automated immunoassay (Elecsys) for assessment of the 25(OH)D(3) status in a cohort of 300 randomly selected patients' samples compared with the reference method liquid chromatography-tandem mass spectrometry (LC-MS/MS).
Passing-Bablok regression analysis demonstrated a slope for each method compared with LC-MS/MS that varied from 0.62 (IDS-EIA) to 1.0 (HPLC). The Advantage and the Liaison 1 showed significant deviation from linearity with highly variable individual results vs. the LC-MS/MS. Difference plots revealed a considerable persistent proportional bias for the IDS-RIA and IDS-EIA. All evaluated methods except HPLC demonstrated a more or less considerable deviation of individual 25(OH)D(3) values compared with LC-MS/MS defined target concentrations.
Standardization of methods for the quantification of 25(OH)D on a human-based sample panel by means of LCMS/MS would help to reduce the inter-method variability with respect to accuracy existing in 25(OH)D measurement considerably. However, there will still remain differences in the accuracy of methods utilizing sample purification before final quantification or immunological reaction when compared with those methods without separate sample purification.
评估维生素D状态最可靠的方法是测量血浆25-羟基维生素D（25[OH]D）浓度。由于所使用的检测技术以及缺乏针对参考物质和参考方法的标准化，25（OH）D测量结果存在高度变异性，这常常混淆了对维生素D状态的正确评估。
我们评估了六种常规可用方法的准确性：高效液相色谱法（HPLC）、IDS放射免疫分析法（IDS-RIA）和酶免疫分析法（IDS-EIA）、Nichols Advantage自动蛋白结合分析法（Advantage）、两种版本的DiaSorin自动免疫分析法（Liaison 1和Liaison 2）以及一种原型自动免疫分析法（Elecsys），用于评估300例随机选择患者样本队列中的25（OH）D（3）状态，并与参考方法液相色谱-串联质谱法（LC-MS/MS）进行比较。
通过Passing-Bablok回归分析表明，与LC-MS/MS相比，每种方法的斜率从0.62（IDS-EIA）到1.0（HPLC）不等。Advantage和Liaison 1与LC-MS/MS相比显示出明显的线性偏差，个体结果高度可变。差异图显示IDS-RIA和IDS-EIA存在相当大的持续比例偏差。与LC-MS/MS定义的目标浓度相比，除HPLC外，所有评估方法的个体25（OH）D（3）值或多或少都存在相当大的偏差。
通过LCMS/MS对基于人样本的25（OH）D定量方法进行标准化，将有助于大幅降低25（OH）D测量中现有方法间在准确性方面的变异性。然而，与那些无需单独样本纯化的方法相比，在最终定量或免疫反应前使用样本纯化的方法在准确性上仍会存在差异。
