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

Abstract

Objective: Urinary 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.

Methods: Antigen-excess, imprecision, interference, linearity, recovery, sample stability and reference values were evaluated on Cobas c501.

Results: The 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.

Conclusions: The urinary cystatin C assay verified to be a reliable assay with convenient performance characteristics, enabling routine testing on clinical chemistry platforms.