Abstract:

Objective　 To evaluate the analysis performance for 7 cystatin C (Cys C ) analysis systems. Methods　 A total of 5 particle-enhanced turbidimetric immunoassay (PETIA) systems and 1 sol particle immunoassay (SPIA) system were evaluated according to the documents of the Clinical and Laboratory Standards Institute (CLSI),and their correlation with particle-enhanced nephelometric immunoassay (PENIA) system from the SIEMENS BNⅡ system (BNⅡ system), precision,accuracy,limit of blank (LoB) and anti-interference ability were evaluated. Results　 For 6 systems (A-F) and BNⅡ system, the total within-run coefficients of variation (CV) were all＜3.75%, and except E, the total between-run CV were all<5%, when Cys C concentration was 0.8-5.0 mg/L. For A-E and BNⅡ systems,accuracy verification showed that the absolute biases for measuring ERM-DA471 were 0.00,0.00,1.01,-0.01,-0.50 and -0.35 mg/L respectively,and the relative biases were 0%,0%,18.43%,-0.18%,-9.12% and -6.39% respectively. The measurement of CAP external quality assessment materials showed that D and BNⅡ systems had desirable results. The LoB were 0.00,0.00,0.31,0.01,0.10,0.06 and<0.05 mg/L for A-F and BNⅡ systems, respectively. When Hb≤13 g/L and TG ≤28 mmol/L,A,B and BNⅡ systems were not significantly influenced (interference＜±10% ). Other systems were influenced with different levels. The A-F systems correlated well with BNⅡ system, and the correlation coefficients (r) were all＞0.975 (P< 0.01). Compared with BN Ⅱ system,the average deviations were -0.02,-0.10,-0.31,0.05,0.04 and 0.36 mg/L for A-F systems, respectively. Conclusions　 The maximum bias can reach 1 mg/L when measuring the reference materials for Cys C analysis systems,and the maximum relative bias is 18.43%. The results of PENIA system are lower than those of PETIA system when measuring ERM-DA471 and CAP external quality assessment materials. In a part of analysis systems, analysis performance is not good.

Key words: Cystatin C, Particle-enhanced turbidimetric immunoassay system, Particle-enhanced nephelometric immunoassay system, Sol particle immunoassay system