Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria.
Department of Clinical Chemistry, University of Liège, Liège, Belgium.
Clin Chem Lab Med. 2021 Nov 2;60(1):74-81. doi: 10.1515/cclm-2021-0792. Print 2022 Jan 26.
In-house developed liquid-chromatography mass spectrometry (LC-MS/MS) methods are used more and more frequently for the simultaneous quantification of vitamin D metabolites. Among these, 24,25-dihydroxyvitamin D3 (24,25(OH)D) is of clinical interest. This study assessed the agreement of this metabolite in two validated in-house LC-MS/MS methods.
24,25(OH)D was measured in 20 samples from the vitamin D external quality assurance (DEQAS) program and in a mixed cohort of hospital patients samples (n=195) with the LC-MS/MS method at the Medical University of Graz (LC-MS/MS 1) and at the University of Liège (LC-MS/MS 2).
In DEQAS samples, 24,25(OH)D results with LC-MS/MS 1 had a proportional bias of 1.0% and a negative systemic difference of -0.05%. LC-MS/MS 2 also showed a proportional bias of 1.0% and the negative systemic bias was -0.22%. Comparing the EQA samples with both methods, no systemic bias was found (0.0%) and the slope was 1%. The mean difference of 195 serum sample measurements between the two LC-MS/MS methods was minimal (-0.2%). Both LC-MS/MS methods showed a constant bias of 0.31 nmol/L and a positive proportional bias of 0.90%, respectively.
This study is the first to assess the comparability of 24,25(OH)D concentrations in a mixed cohort of hospitalized patients with two fully validated in-house LC-MS/MS methods. Despite different sample preparation, chromatographic separation and ionization, both methods showed high precision measurements of 24,25(OH)D. Furthermore, we demonstrate the improvement of accuracy and precision measurements of 24,25(OH)D in serum samples and in the DEQAS program.
越来越多的实验室采用液相色谱-质谱联用（LC-MS/MS）方法来同时定量检测维生素 D 代谢物。其中，24,25-二羟维生素 D3（24,25(OH)D）具有重要的临床意义。本研究旨在评估两种经过验证的实验室自建 LC-MS/MS 方法检测 24,25(OH)D 的一致性。
采用 Graz医科大学（LC-MS/MS 1）和列日大学（LC-MS/MS 2）的 LC-MS/MS 方法，分别对维生素 D 外部质量保证（DEQAS）计划中的 20 个样本和混合住院患者样本（n=195）中的 24,25(OH)D 进行了检测。
在 DEQAS 样本中，LC-MS/MS 1 检测的 24,25(OH)D 结果存在 1.0%的比例偏差和-0.05%的负系统差异。LC-MS/MS 2 也显示出 1.0%的比例偏差和-0.22%的负系统偏差。将 EQA 样本与两种方法进行比较，未发现系统偏差（0.0%），斜率为 1%。两种 LC-MS/MS 方法检测的 195 例血清样本的平均差值最小（-0.2%）。两种 LC-MS/MS 方法的检测结果均存在 0.31 nmol/L 的恒定偏差和 0.90%的正比例偏差。
本研究首次评估了两种完全验证的实验室自建 LC-MS/MS 方法在混合住院患者群体中检测 24,25(OH)D 浓度的可比性。尽管采用了不同的样品制备、色谱分离和离子化方法，但两种方法均能实现 24,25(OH)D 的高精度测量。此外，我们还证明了在血清样本和 DEQAS 计划中，24,25(OH)D 的准确度和精密度测量得到了提高。
