Evaluation of NGAL TestTM on Cobas 6000.
BACKGROUND
Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a promising biomarker for acute kidney injury (AKI). Our objectives were to evaluate the NGAL Test(TM) from Bioporto for both urine NGAL and plasma NGAL on the Cobas 6000 c501 (Roche Diagnostics, Rotkreuz, Switzerland) with matched measurements run on Hitachi 917, the method's linearity on the Cobas 6000 in urine, EDTA and Lithium-Heparin (Li-Hep), the influence of using EDTA or Li-Hep tubes and, finally, the impact of freezing and thawing on the sample.


METHODS
Forty matched samples of Li-Hep and EDTA plasma and 40 urine samples were analyzed for method, anticoagulant, and freeze-thaw comparisons. Linearity was assessed using high NGAL samples diluted in urine, EDTA, and Li-Hep plasma. Commercial internal controls were used for the imprecision study.


RESULTS
The Cobas 6000 measured identically with the Hitachi 917, however, not in EDTA plasma (Median Difference = 17.50 μg/L, p < 0.0001). Freeze-thaw process reduced NGAL ((EDTA: Mean Difference = = 15.13 μg/L, p = 0.0014)(Li-Hep: Median Difference = = 6.5 μg/L, p = 0.0129)). NGAL results were higher in Li-Hep plasma than in EDTA plasma ((Non-thawed: Median Difference = = 14.5 μg/L, p < 0.0001), (Thawed: Median Difference = = 21.5 μg/L, p = 0.0003)). Linearity agreements were observed in all three specimens. Imprecision (CV%) was below 3%.


CONCLUSIONS
The NGAL Test(TM) can be applied on the Cobas 6000 with acceptable performance, although the Cobas 6000 measured higher than the Hitachi 917 in EDTA plasma. Though clinically insignificant, we found that the freeze-thaw process had a reduced effect. NGAL results were higher in Li-Hep tubes than in EDTA tubes. Thus, for blood samples we recommend use of EDTA tubes for NGAL measurements.
Department of Clinical Biochemistry, Hvidovre Hospital , Denmark.
Young B L
YB
Hansen
Anette
A
Damgaard
Jørgen H
JH
Poulsen
D058186:Acute Kidney Injury / Q000097:blood / Q000175:diagnosis / Q000652:urine*; D000209:Acute-Phase Proteins / Q000652:urine*; D000925:Anticoagulants / Q000737:chemistry; D001774:Blood Chemical Analysis / Q000295:instrumentation* / Q000592:standards; D004492:Edetic Acid / Q000737:chemistry; D006493:Heparin / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D000071068:Lipocalin-2; D054834:Lipocalins / Q000097:blood / Q000652:urine*; D011518:Proto-Oncogene Proteins / Q000097:blood / Q000652:urine*; D012015:Reference Standards; D015203:Reproducibility of Results; D016482:Urinalysis / Q000295:instrumentation* / Q000592:standards
D000209:Acute-Phase Proteins; D000925:Anticoagulants; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D006493:Heparin; D004492:Edetic Acid