Cystatin C is a reliable marker for estimation of glomerular filtration rate in renal transplantation: validation of a new turbidimetric assay using monospecific sheep antibodies

摘要

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 performanceof this new assay was evaluated. Clinical relevance was determined by comparison with areference method in a cohort of kidney transplant patients.Patients and methods: First, the analytical performance of the Binding Site cystatin C kitwas tested on SPAPLUS® and Hitachi® analyzers. Second, a comparison study was performedusing SPAPLUS® analyzer against two other cystatin C methods (the Siemens-PENIA methodon BNII® and the Dako-PETIA application on Olympus AU640®). Third, the glomerularfiltration rate (GFR) was estimated using several predictive cystatin C- and creatinine-basedequations and compared to GFR measured by an isotopic method (99mTc-DTPA). Thesepredictive algorithms were analyzed with respect to bias, precision and accuracy.Results: Total intra-assay and inter-assay coefficients of variation were below 5%. Valuesobtained with the SPAPLUS® correlated with the Siemens-PENIA and the Dako-PETIAmethods. The creatinine and cystatin C-based equation allowed reliable assessment of GFR inour population of renal transplantation.Conclusions: The use of algorithms based on cystatin C and creatinine could provide areliable estimate of GFR in kidney transplantation.