AUTHOR=Cody Ellen M. , Rose James E. , Huang Bin , Qiu Tingting , Brunner Hermine I. , Devarajan Prasad 

TITLE=Stability of novel urinary biomarkers used for lupus nephritis

JOURNAL=Frontiers in Pediatrics

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2022.974049

DOI=10.3389/fped.2022.974049

ISSN=2296-2360

ABSTRACT=Background: The Renal Activity Index for Lupus (RAIL), is a composite score of six urinary biomarkers (neutrophil gelatinase–associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP-1), kidney injury molecule-1 (KIM-1), ceruloplasmin, adiponectin, and hemopexin) used to monitor lupus nephritis activity in children. We tested stability of RAIL biomarkers prior to meaningful clinical use. 
Methods: Urine samples were tested by ELISA under shipping conditions, freeze/thaw, ambient and longer-term storage. Statistical analysis was performed via Deming Regression, Bland-Altman and Spearman Correlation Coefficient.
Results: Biomarker concentration were comparable to freshly collected urine following storage at -80C for up to 3 months, and at 4 or 25C up to 48 hours followed by -80C. Neither shipping on dry or wet ice exposure nor addition of two freeze-thaw cycles led to loss of signal, with excellent Spearman Correlation coefficients under all conditions.
Conclusions: RAIL biomarkers are stable following short-term storage at clinically relevant conditions.