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

OBJECTIVES: Cystatin 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 METHODS: We 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. RESULTS: The 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 6g/dl interfered with the assay. The assay agreed well with the Siemens assay. CONCLUSION: The 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.

Multicentre physiological reference values for some urinary component-to-creatinine (creatininium) concentration ratios.

Nine clinical laboratories in different regions of Spain have shared the search for reference individuals and the production of reference values for urinary component-to-creatininium concentration ratios measured in first morning urine samples using RD/Hitachi analysers. These urinary quantities include albumin, calcium(II), chloride, magnesium(II), phosphate, potassium ion, protein, sodium ion, urate and urea. All the logistic work was done in co-operation with the reagents' and analysers' supplier (Roche Diagnostics España, S.L., Sant Cugat del Vallès, Catalonia, Spain). From the blend of reference values obtained by each laboratory, the multicentre reference limits were estimated parametrically after mathematical transformation of original data.