Background: Acute Kidney Injury (AKI) is a common and serious complication following cardiac surgery, associated with adverse outcomes and increased healthcare costs. Early identification of AKI is critical for timely intervention and improved prognosis. However, serum creatinine—the traditional biomarker for renal function—lacks sensitivity in the early stages due to its delayed rise. Neutrophil Gelatinase-Associated Lipocalin (NGAL) has emerged as a promising early biomarker. Objective: This study aimed to compare the diagnostic performance of urinary NGAL versus serum creatinine for early prediction of AKI in post-cardiac surgery patients. Methodology: This descriptive cross-sectional study was conducted from May 2023 to June 2024 and included 123 patients aged 40–70 years undergoing elective cardiac surgery. Patients with pre-existing chronic kidney disease or recent urological procedures were excluded. Urinary NGAL levels were measured 2 hours postoperatively, while serum creatinine was assessed at 48 hours. Diagnostic performance was evaluated in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy. Results: Urinary NGAL demonstrated superior diagnostic accuracy with a sensitivity of 92.0%, specificity of 81.25%, PPV of 88.46%, NPV of 86.67%, and overall accuracy of 87.80% in predicting AKI. In comparison, serum creatinine exhibited lower diagnostic metrics, reinforcing the early predictive value of NGAL. Conclusion: Urinary NGAL outperforms serum creatinine as an early biomarker for AKI following cardiac surgery. Incorporating urinary NGAL testing into routine postoperative care may enhance early detection and improve clinical outcomes. Further large-scale, multicenter studies are warranted to validate these findings across diverse populations. Keywords: Acute Kidney Injury, Biomarker, Cardiac Surgery, Neutrophil Gelatinase-Associated Lipocalin, Serum Creatinine.
Sarfraz et al. (Sat,) studied this question.