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.
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 SPA(PLUS)® and Hitachi® analyzers. Second, a comparison study was performed using SPA(PLUS)® 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 (⁹⁹(m)Tc-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 SPA(PLUS)® 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.
Department of Biochemistry, University of Montpellier 1, Montpellier, France.
Anne-Sophie
AS
Bargnoux
Etienne
E
Cavalier
Jean-Paul
JP
Cristol
Noémie
N
Simon
Anne-Marie
AM
Dupuy
Valérie
V
Garrigue
Stéphanie
S
Badiou
Pierre
P
Delanaye
Georges
G
Mourad
D000818:Animals; D000906:Antibodies / Q000276:immunology*; D000918:Antibody Specificity; D001665:Binding Sites; D015415:Biomarkers / Q000032:analysis; D003404:Creatinine / Q000032:analysis / Q000276:immunology; D055316:Cystatin C / Q000032:analysis* / Q000276:immunology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D007202:Indicators and Reagents / Q000378:metabolism; D016030:Kidney Transplantation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation / Q000379:methods*; D012756:Sheep; D016284:Technetium Tc 99m Pentetate / Q000378:metabolism
D000906:Antibodies; D015415:Biomarkers; D055316:Cystatin C; D007202:Indicators and Reagents; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate