Particle enhanced turbidimetric immunoassay for the determination of urine cystatin C on Cobas c501

ObjectiveUrinary cystatin C has been reported to be a good marker for tubular damage and acute kidney injury. The aim of this study was to develop a high throughput assay for the quantification of urine cystatin C.MethodsAntigen-excess, imprecision, interference, linearity, recovery, sample stability and reference values were evaluated on Cobas c501.ResultsThe assay was linear over the dynamic range of the study (R2 = 0.9994). The total assay imprecision was below 5%. The assay recovery was estimated at 87–100%. No tendency to antigen-excess (up to 35 mg/L), nor interference with haemoglobin (1.25–10 g/L) was observed. Cystatin C was stable for 1 day at ambient temperature (19–23 °C) but for 2 days at + 4 °C. The reference interval for cystatin C in urine was < 0.414 mg/L.ConclusionsThe urinary cystatin C assay verified to be a reliable assay with convenient performance characteristics, enabling routine testing on clinical chemistry platforms.

► Acute kidney injury is an intensive care disorder with high mortality.
► Human cystatin C is synthesised by all nucleated cells and exist in all body fluids.
► We have evaluated Gentians cystatin C reagents for urine samples on Cobas c501.
► The Cystatin C method is verified to employ for analyse of urine.
► On the Cobas system the method can be available 24 hours a day.