Department of Laboratory Medicine, School of Medicine, Wonkwang University, Iksan, Korea.
Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Ann Lab Med. 2023 Nov 1;43(6):565-573. doi: 10.3343/alm.2023.43.6.565. Epub 2023 Jun 30.
Serum cystatin C (cysC), which is less affected by sex, race, and muscle mass than creatinine, is a useful biomarker of the estimated glomerular filtration rate (eGFR). The standardization of cysC measurements remains controversial, although a certified reference material (ERM-DA471/IFCC) is available. Moreover, the effect of combinations of cysC reagents and equations for eGFR is unclear.
We conducted a simulation analysis of cysC measured using two reagents standardized against ERM-DA471/IFCC-Gentian cystatin C immunoassay (Gentian; GentianAS, Moss, Norway) and Roche Tina-quant Cystatin C Gen.2 (Roche; Roche, Mannheim, Germany)-on a Cobas c702 system (Roche) and eGFR generated by eight combinations of four equations: 2012 cystatin C-based Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI); the Caucasian, Asian, pediatric, and adult equation (CAPA); full age spectrum equation (FAS); and 2023 cystatin C-based European Kidney Function Consortium equation (EKFC).
A total of 148 participants (mean age, 60.5±14.5 years; 43% female) were enrolled. The mean cysC was 1.72±1.44 mg/L for Gentian and 1.71±1.35 mg/L for Roche. Regression analysis showed concordance between the reagents within 0.85-4.40 mg/L when using ±7.61% total allowable error. Lin's concordance correlation coefficient of eGFR, by combining the measuring system and equation, varied from 0.73 to 1.00.
The equivalence of cysC values at low concentrations (<0.85 mg/L) between the two reagents was unsatisfactory. Results obtained with different measurement systems could lead to larger differences in eGFR varying with the combination.
血清胱抑素 C（cysC）比肌酐受性别、种族和肌肉量的影响更小，是估计肾小球滤过率（eGFR）的有用生物标志物。尽管有认证参考物质（ERM-DA471/IFCC）可用，但 cysC 测量的标准化仍存在争议。此外，cysC 试剂组合和 eGFR 方程的效果尚不清楚。
我们对使用两种试剂测量的 cysC 进行了模拟分析，这两种试剂均参照 ERM-DA471/IFCC-Gentian 胱抑素 C 免疫测定（Gentian；GentianAS，莫斯，挪威）和罗氏 Tina-quant Cystatin C Gen.2（罗氏；罗氏，曼海姆，德国）-在 Cobas c702 系统（罗氏）上进行，并使用八个组合的四个方程生成 eGFR：2012 年基于胱抑素 C 的慢性肾脏病流行病学合作组方程（CKD-EPI）；白种人、亚洲人、儿科和成人方程（CAPA）；全年龄谱方程（FAS）；以及 2023 年基于胱抑素 C 的欧洲肾脏功能联合会方程（EKFC）。
共纳入 148 名参与者（平均年龄 60.5±14.5 岁；43%为女性）。Gentian 的 cysC 平均值为 1.72±1.44mg/L，罗氏的 cysC 平均值为 1.71±1.35mg/L。回归分析显示，当使用 ±7.61%总允许误差时，两种试剂在 0.85-4.40mg/L 之间具有一致性。通过结合测量系统和方程，eGFR 的 Lin 一致性相关系数在 0.73 到 1.00 之间变化。
两种试剂在低浓度（<0.85mg/L）时 cysC 值的等效性不理想。不同测量系统获得的结果可能会导致 eGFR 的差异随着组合的不同而增大。
