#1504 Performance evaluation of MicroVue sC5b-9 for analysis of urine samples

Abstract

Abstract Background and Aims Complement mediated kidney diseases including C3 glomerulopathy (C3G), atypical uremic syndrome (aHUS), lupus nephritis (LN), and immunoglobulin A nephropathy (IgAN) are chronic inflammatory conditions characterized by dysregulated complement activation. Traditionally, complement activation is measured in plasma. However, patients with kidney disease often have an abundance of complement activation fragments in their urine—including soluble C5b-9 (sC5b-9), a marker of terminal pathway activation—highlighting the potential value of sC5b-9 measurement in urine for diagnosis and risk management in patients with C3G, aHUS, LN, IgAN, and other kidney diseases. Herein we evaluated the analytical performance of the Quidel MicroVue sC5b-9 Plus EIA for measurement of sC5b-9 in urine. Method The Quidel MicroVue sC5b-9 Plus EIA was evaluated using randomly collected healthy urine samples or healthy urine samples spiked with a known concentration of sC5b-9, as well as chronic kidney disease (CKD) urine samples. Results The analytical performance of the Quidel MicroVue sC5b-9 Plus EIA for measurement of sC5b-9 in urine met acceptability criteria for accuracy and precision. Assay accuracy was (100 ± 20%) and intra-assay precision as well as inter-assay precision was ≤ 11% coefficient of variability (CV). sC5b-9 was not detected in healthy urine samples (N = 40), but sC5b-9 was detected in a subset of urine samples from patients with CKD (N = 10). Positive linearity was observed over a wide range of concentrations. sC5b-9 measured in urine was not affected by hemoglobin or triglyceride, and was stable following three freeze-thaw cycles. Lastly, sC5b-9 measured in urine was stable when stored at −20°C and –80°C for 4 weeks. Long term stability testing at –80°C is underway. Conclusion Quidel MicroVue sC5b-9 Plus EIA is an accurate, reliable assay for detection of sC5b-9 in urine samples.