Comparison of Two Methods for Determination of NGAL Levels in Urine: ELISA and CMIA

Abstract

Background: Neutrophil gelatinase-associated lipocalin (NGAL) is a new useful biomarker for the early diagnosis of acute kidney injury. The aim of the study was to compare two analytical methods for measurement of urinary NGAL: enzyme-linked immunosorbent assay (ELISA) and chemiluminescent microparticle immunoassay (CMIA). Methods: Two assays were used to measure urinary NGAL: ELISA kit (R&D Systems) and ARCHITECT Urine NGAL (Abbott Laboratories). The study material was the urine obtained from 30 healthy subjects (mean age 56.4 ± 15.2). Results: The median value and interquantile range of urinary NGAL in the studied group measured by ELISA (R&D Systems) were 3.5 ng/ml (1.2; 6.6) and by CMIA (ARCHITECT Urine NGAL assay, Abbott Diagnostics) were 4.4 ng/ml (1.9; 9.4). Levels of urinary NGAL obtained by CMIA were significantly higher than by ELISA. There was a significant positive correlation between the concentration of urinary NGAL determined by both methods (r = 0.8625, P < 0.01). Conclusion: The comparison of individual data obtained by ELISA and CMIA should be taken with care. From laboratory's point of view, ELISA is less expensive than CMIA method for the determination of NGAL in urine. However, CMIA method allows rapid determination of urinary NGAL concentration through automated assay.