Analytical performance evaluation of a particle-enhanced turbidimetric cystatin C assay on the Roche COBAS 6000 analyzer

ObjectivesCystatin C is a low molecular protein that has been proposed to estimate the glomerular filtration rate. Here we investigated the performance of the Roche cystatin C assay on the COBAS 6000 analyzer.Design and methodsWe studied the imprecision, recovery, limit of detection and quantification, linearity and interferences. For method comparison, split sample aliquots were assayed using the described method and a Siemens cystatin C assay.ResultsThe assay displayed a low total imprecision and a good linearity over the entire range tested. Bilirubin and triglycerides did not interfere with the assay, and only a haemoglobin concentration higher than 6 g/dl interfered with the assay. The assay agreed well with the Siemens assay.ConclusionThe Roche cystatin C assay is an acceptable method for determining the cystatin C and the glomerular filtration rate estimate. On a COBAS 6000, the assay improves and simplifies the laboratory's workload.