Résumé
Background: The potential use of cystatin C was recently assessed in kidney transplantation. A new particle-enhanced turbidimetric immunoassay (PETIA) that uses sheep antibodies (Binding Site human cystatin C immunoassay) has been developed. Analytical performance of this new assay was evaluated. Clinical relevance was determined by comparison with a reference method in a cohort of kidney transplant patients. Methods: First, the analytical performance of the Binding Site cystatin C kit was tested on SPAPLUS® and Hitachi® analyzers. Second, a comparison study was performed using SPAPLUS® analyzer against two other cystatin C methods (the Siemens-PENIA method on BNII® and the Dako-PETIA application on Olympus AU640®). Third, the glomerular filtration rate (GFR) was estimated using several predictive cystatin C- and creatinine-based equations and compared to GFR measured by an isotopic method (99mTc-DTPA). These predictive algorithms were analyzed with respect to bias, precision and accuracy. Results: Total intra-assay and inter-assay coefficients of variation were below 5%. Values obtained with the SPAPLUS® correlated with the Siemens-PENIA and the Dako-PETIA methods. The creatinine and cystatin C-based equation allowed reliable assessment of GFR in our population of renal transplantation. Conclusions: The use of algorithms based on cystatin C and creatinine could provide a reliable estimate of GFR in kidney transplantation.