Enhanced Immunoassay Validated for NGAL

The concentration of the biomarker NGAL increases considerably immediately after acute kidney injury (AKI). The measurement of NGAL in serum or plasma is also considered to be more convenient than measurement in urine, since urine output may be considerably reduced in patients with AKI.

Scientists at the University of Verona (Italy) designed a study to validate the analytical performance of the new particle-enhanced enhanced turbidimetric immunoassay (PETIA) for measuring neutrophil gelatinase-associated lipocalin (NGAL) in serum samples. The analytical validation of the NGAL PETIA consisted of calculation of limit of blank (LOB), limit of detection (LOD) and functional sensitivity, and estimation of inter-assay and intra-assay imprecision, linearity, and correlation with another widely used NGAL PETIA.

The Gentian NGAL is a particle-enhanced turbidimetric immunoassay (PETIA), which can be applied to a vast array of automated clinical chemistry analyzers. Analytical validation of the Gentian NGAL assay was carried out on a Cobas c501. The quoted NGAL serum/plasma reference range is 13.7 ng/mL to 104.6 ng/mL, the total sample volume needed for the assay is 3 μL and test results are available in 10 minutes.

An excellent correlation was observed between values measured with Gentian NGAL and BioPorto NGAL in 74 routine serum samples. The LOB and LOD of Gentian NGAL were found to be 3.8 ng/mL and 6.3 ng/mL, respectively. An analytical coefficient of variation (CV) of 20% corresponded to a NGAL value of 10 ng/mL. The intra-assay and inter-assay imprecision (CV) was between 0.4% and 5.2% and 0.6% and 7.1% and the total imprecision (CV) was 3.7%. The linearity was optimal at NGAL concentrations between 37 and 1,420 ng/mL.

The authors concluded that the result of their analytical validation show that Gentian NGAL may be a viable option for both routine and urgent assessment of serum NGAL. Additional advantages are the very fast turnaround time as results are available in approximately 10 minutes compared to 35 minutes in another commercial assay and two hours in an enzyme-linked immunosorbent assay (ELISA). The possibility of widespread implementation of this test on a wide array of clinical chemistry platforms may also permit the concomitant measurement of NGAL and other biomarkers of renal function. The full study will be published in the August 2017 issue of the journal Practical Laboratory Medicine.

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University of Verona