Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA.
Clin Chem Lab Med. 2012 Mar 30;50(9):1591-6. doi: 10.1515/cclm-2012-0063.
Cystatin C is an alternative biomarker for assessing glomerular filtration rate (GFR), yet lack of standardization could hinder its widespread use. In this study we analytically and clinically validated a newer cystatin C particle-enhanced turbidimetric assay (PETIA) traceable to a certified reference material and compared it to the more commonly used particle-enhanced nephelometric assay (PENIA).
Samples from four patient cohorts at the Mayo Clinic were studied: 1) clinical convenience samples (n=50); 2) samples from patients undergoing iothalamate urinary clearance testing for clinical indications (n=101); 3) volunteers without kidney disease (n=292); 4) samples from 1999-2000 with previous cystatin C measurements.
The cystatin C PETIA was analytically robust between 0.15 mg/L and 8.36 mg/L. PETIA cystatin C values were 27.5% higher than PENIA results. Furthermore, PENIA results were 12.9% lower in 2010 than in 2000. PETIA cystatin C values and existing equations performed reasonably well to estimate GFR with an overall -7.4% bias for all patients analyzed. Age and gender specific reference intervals were established for the PETIA cystatin C.
Cystatin C can be precisely measured by PETIA traceable to the international reference material, ERM-DA471/IFCC, using a routine chemistry autoanalyzer. There are important biases between this assay and the widely employed Siemens PENIA. This study highlights the importance of assay standardization if cystatin C is to be widely used to estimate GFR.
胱抑素 C 是评估肾小球滤过率（GFR）的替代生物标志物，但缺乏标准化可能会阻碍其广泛应用。在这项研究中，我们对一种新型的胱抑素 C 颗粒增强比浊法（PETIA）进行了分析和临床验证，该方法可溯源至经过认证的参考物质，并将其与更常用的颗粒增强散射比浊法（PENIA）进行了比较。
本研究对 Mayo 诊所的四个患者队列的样本进行了研究：1）临床便利样本（n=50）；2）因临床指征接受碘海醇尿液清除试验的患者样本（n=101）；3）无肾脏疾病的志愿者（n=292）；4）来自 1999-2000 年且之前有胱抑素 C 测量值的样本。
胱抑素 C PETIA 在 0.15mg/L 至 8.36mg/L 之间具有良好的分析稳定性。PETIA 胱抑素 C 值比 PENIA 结果高 27.5%。此外，2010 年的 PENIA 结果比 2000 年低 12.9%。PETIA 胱抑素 C 值和现有的方程在估计所有分析患者的 GFR 方面表现相当，总体偏差为-7.4%。建立了 PETIA 胱抑素 C 的年龄和性别特异性参考区间。
使用常规化学自动分析仪，通过可溯源至国际参考物质 ERM-DA471/IFCC 的 PETIA 可精确测量胱抑素 C。该检测方法与广泛应用的西门子 PENIA 之间存在重要偏差。本研究强调了如果要广泛使用胱抑素 C 来估计 GFR，则需要进行检测方法标准化。
