[Clinical validity of renal function markers including serum cystatin C on chronic kidney disease classification]

In this study, clinical utility of various renal function markers (Cystatin C, Creatinine, beta2-microglobulin, Urea nitrogen) including serum Cystatin C was evaluated by the latex turbidimetric immunoassay based on the Chronic Kidney Disease (CKD) stage classification. Serum creatinine was most correlated with estimated Glomerular Filtration Rate (eGFR), followed by serum Cystatin C. However, the level of serum Cystatin C increased significantly earlier than other renal function markers in the group of mild renal dysfunction based on the CKD stage classification. Cystatin C also had the most distinctive ability of the renal dysfunction by Receiver Operating Characteristic (ROC) and distinction characteristic analysis. Thus, it is useful to measure serum Cystatin C and serum creatinine at the same time to improve diagnostic sensitivity and specificity, eGFR was 6% higher than Ccr on stage III-V, though Ccr was 30% higher than eGFR on stage I-II by CKD stage classifications. Since eGFR and Ccr showed different results in early and severe CKD groups, it was suggested that Ccr and eGFR need to be evaluated as different renal function markers.