Performance evaluation of a particle-enhanced turbidimetric cystatin C assay using the Abbott Aeroset analyser and assessment of cystatin C-based equations for estimating glomerular filtration rate in chronic kidney disease.

INTRODUCTION Measurement of glomerular filtration rate (GFR) is critical for the diagnosis and stratification of chronic kidney disease (CKD). Recent studies have shown that cystatin C is superior to creatinine for the detection of impaired GFR, and several cystatin C-based equations for estimating GFR have been developed for this clinical application. We conducted the present study to assess the applicability of cystatin C as a routine clinical laboratory index and to determine the performance of cystatin C-based equations in estimating GFR in CKD patients in China. METHODS Performance evaluation of particle-enhanced turbidimetric cystatin C assay on the Abbott Aeroset analyser was carried out according to the National Committee for Clinical Laboratory document EP10-A2. Estimated GFR, which was generated from cystatin C-based equations, was compared with measured GFR, which was detected by plasma clearance of 99mTc-DTPA. RESULTS Our cystatin C assay showed a very low total imprecision and linearity drift. All eight cystatin C-based GFR estimating equations underestimated or overestimated GFR as compared with GFR determined by 99mTc-DTPA clearance. CONCLUSION Although the cystatin C assay is acceptable for routine clinical laboratory monitoring, none of the existing cystatin C-based equations were ideal for estimating GFR in Chinese CKD patients.