A longitudinal prospective study investigating serial measurements of plasma neutrophil gelatinase-associated lipocalins (NGAL) for the prediction of chronic kidney disease and acute kidney injury in emergency department patients

Acute kidney injury (AKI) and chronic kidney disease (CKD) are associated with high morbidity. Current diagnostic markers, e.g., creatinine (Cr) and estimated glomerular filtration rate (eGFR), lack precision in early kidney disease detection. Neutrophil gelatinase-associated lipocalin (NGAL) has been proposed as a more sensitive biomarker for kidney injury. This study examined the effectiveness of plasma NGAL (pNGAL) as biomarker for CKD and AKI prediction in an emergency department (ED) setting and for predicting the presence of CKD and AKI in future admissions (readmission). The performance was compared to that of C-reactive protein (CRP). A prospective longitudinal study was conducted at North Zealand University Hospital in Denmark, including 925 patients admitted to the ED. pNGAL and CRP were measured at admission, with follow-up pNGAL measurements for hospitalized patients. CKD and AKI were defined according to KDIGO guidelines. Receiver operating characteristic (ROC) analyses assessed the sensitivity, specificity, and predictive value of pNGAL and CRP, for AKI and CKD, at both admission and readmission. pNGAL is useful for ruling out AKI and CKD, especially at admission, but its low PPV limit its diagnostic accuracy, particularly at readmission. It is more effective as a screening tool rather than a standalone diagnostic marker. Higher predictive performance was observed for pNGAL compared to CRP. For serial pNGAL measurements, CKD patients exhibited higher initial levels at admission, but these differences diminished by day four, with considerable variability observed thereafter.