A comparison of the analytical performance of five commercially available assays for neutrophil gelatinase-associated lipocalin using urine

Abstract

Background: Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker for acute kidney injury that is beginning to be used in clinical practice in addition to research studies. The current study describes an independent validation and comparison of five commercially available NGAL assays, focusing on urine samples. This is an essential step in the translation of this marker to clinical use in terms of allowing valid inter-study comparison and generation of robust results. Methods: Two CE (Conformité Europé enne)-marked assays, the NGAL Test (BioPorto) on Siemens ADVIA w 1800 and the ARCHITECT Urine NGAL assay on i2000SR (Abbott Laboratories), and three research-use-only (RUO) ELISAs (R&D Systems, Hycult and BioPorto) were evaluated. Imprecision, parallelism, recovery, selectivity, limit of quantitation (LOQ), vulnerability to interference and hook effect were assessed and inter-assay agreement was determined using 68 urine samples from patients with various renal diseases and healthy controls. Results: The Abbott and R&D Systems assays demonstrated satisfactory performance for all parameters tested. However for the other three assays evaluated, problems were identified with LOQ (BioPorto/ADVIA w ), parallelism (BioPorto ELISA) or several parameters (Hycult). Between-method agreement varied with the Hycult assay in particular being markedly different and highlighting issues with standardization and form of NGAL measured. Conclusions: Variability exists between the five NGAL assays in terms of their performance and this should be taken into account when interpreting results from the various clinical or research studies measuring urinary NGAL.

Calculations for Adjusting Endogenous Biomarker Levels During Analytical Recovery Assessments for Ligand-Binding Assay Bioanalytical Method Validation

“…We consider the subtraction method preferred over that of addition to adjust for detectable endogenous biomarker levels in %AR calculations, consistent with opinions of others (e.g., [9][10][11][12][13]20,22,23). The subtraction method can use either mass units or raw assay signal, the latter of which being applicable when the endogenous analyte is present above the LOD, but BLOQ.…”

A comparison of three commercial platforms for urinary NGAL in critically ill adults

“…Such techniques also have the advantage of higher throughput and better reproducibility. Since the introduction of the first commercial immunoassay Architect in 2008 [28], the NGAL turbidimetric immunoassay has been licensed for use on a number of chemistry autoanalyzers, including the Advia 1800, the Advia 2400, and Beckman Coulter AU 5822 [20,21]. The application for the Advia 1800 platform has since then been withdrawn [20].…”

“…For Architect NGAL assay, we did not perform these procedures; instead, we refer to data from a recent publication [19]. Inter-and intra-assay CVs of ≤ 15% and ≤ 10%, respectively, were considered to be acceptable [20].…”

“…A number of studies have evaluated the analytical characteristics of various NGAL assays [17][18][19][20][21], and new methods are continuously launched in the market (http://www. labmark.cz/soubory/bioporto-aplikace-ngal-test-on-siemens-dimension-vista.pdf).…”

Evaluation of a particle enhanced turbidimetric assay for the measurement of neutrophil gelatinase-associated lipocalin in plasma and urine on Architect-8000: Analytical performance and establishment of reference values

“…Several commercial NGAL assays exist which are mostly research-use-only ELISAs, but more recently, assays have been introduced for clinical chemistry analyzers. In the literature, there are a limited number of studies examining the performance of these assays [6,8,9,13].…”