Diagnostic value of serum creatinine versus urinary neutrophil gelatinase-associated lipocalin (uNGAL) in acute kidney injury in resource-limited settings

Objective: To determine the diagnostic accuracy and optimal threshold for the difference between creatinine at 48 hours and creatinine at admission in hospital versus gold standard, urinary neutrophil gelatinase-associated lipocalin (uNGAL) in patients with renal impairment. Methods: A prospective observational study was conducted from February to May 2022, with patients hospitalized in a tertiary care referral hospital. To compare the two diagnostic tests, a urine sample for the uNGAL assay using the Finecare™ NGAL rapid quantitative test, and for creatinine, a blood sample taken at admission and another after 48 hours. Only patients who had both tests were included in the study. Results: A total of 167 patients were included. The two tests were highly correlated (r = 0.33, p<0.001). The ROC area analysis (AUC = 0.8298) demonstrated the accuracy of creatinine in the diagnosis of acute kidney injury (AKI). The optimal threshold using the Liu method was 0.3 mg/dl (sensitivity = 72.9%, specificity = 91.8%). Conclusion: The results suggest that the difference between creatinine at 48 hours and creatinine at intake should continue to be used when diagnosing AKI. In addition, it is a simple test, easy to perform and standardize, and inexpensive compared to the uNGAL.