Clin Chem Lab Med. 2013 Oct;51(10):1971-81. doi: 10.1515/cclm-2013-0208.
There is growing interest in measuring plasma fibroblast growth factor 23 (FGF23) concentration in a number of clinical settings. However, data comparing current commercial intact and C-terminal FGF23 assays is lacking.
We used plasma samples collected from a cohort of healthy adults and patients undergoing chronic haemodialysis therapy (n=67) to compare the precision, recovery, linearity and pre-analytical stability characteristics of four commercial FGF23 assays from Kainos, Millipore and Immutopics Inc. Method agreement was evaluated using Passing-Bablok regression and difference plot analysis.
Both Millipore and Immutopics intact FGF23 kits demonstrated marked negative proportional bias relative to Kainos assay readout, particularly in the haemodialysis group, and poor recovery of purified FGF23 standard at high spiking concentrations. Dilution of high-reading samples with saline as recommended by the Immutopics kit resulted in significant deviation from linearity. Immutopics C-terminal FGF23 concentrations displayed a strong association with intact FGF23 concentrations determined with all three intact assays in the haemodialysis group, but showed no significant correlation within the physiological range. Only intact FGF23 measurements made with the Immutopics assay demonstrated evidence of significant instability 8 h after venepuncture.
Current ELISA kits for plasma intact FGF23 measurement show poor analytical agreement, and cannot be used interchangeably. This is mainly due to differences in calibration. Harmonisation of available assays using a common international standard would facilitate more meaningful interpretation of data from studies using different kits. Discordance between intact and C-terminal FGF23 assay measurements is more marked at physiological concentrations than in patients undergoing haemodialysis.
在许多临床环境中，人们对测量血浆成纤维细胞生长因子 23（FGF23）浓度越来越感兴趣。然而，目前缺乏比较现有商业完整和 C 端 FGF23 检测的相关数据。
我们使用从一组健康成年人和接受慢性血液透析治疗的患者（n=67）收集的血浆样本，比较了 Kainos、Millipore 和 Immutopics Inc. 四家商业 FGF23 检测的精密度、回收率、线性和分析前稳定性特征。使用 Passing-Bablok 回归和差异图分析评估方法间的一致性。
与 Kainos 检测结果相比，Millipore 和 Immutopics 完整 FGF23 试剂盒均显示出明显的负比例偏倚，尤其是在血液透析组中，并且对高浓度添加的纯化 FGF23 标准的回收率较差。根据 Immutopics 试剂盒的建议，用生理盐水稀释高读数样本会导致明显的非线性。Immutopics C 端 FGF23 浓度与血液透析组中所有三种完整检测法测定的完整 FGF23 浓度密切相关，但在生理范围内没有显著相关性。只有 Immutopics 测定的完整 FGF23 测量在静脉穿刺 8 小时后显示出明显的不稳定性。
目前用于测量血浆完整 FGF23 的 ELISA 试剂盒在分析上一致性较差，不能互换使用。这主要是由于校准差异所致。使用共同的国际标准对现有检测方法进行协调，将有助于更有意义地解释使用不同试剂盒进行的研究的数据。在生理浓度下，完整和 C 端 FGF23 检测的测量结果之间的差异比在血液透析患者中更为明显。
