Implications of the changes in serum neutrophil gelatinase‐associated lipocalin and cystatin C in patients with chronic kidney disease

Aim Early intervention in patients with chronic kidney disease (CKD) significantly improves the prognosis. The present widely used markers of renal function, such as serum creatinine (sCr), fail to reflect early renal damage and predict the progression of disease. The authors aimed to evaluate whether neutrophil gelatinase-associated lipocalin (NGAL), a novel specific biomarker of acute kidney injury, could predict the progression of CKD. Methods We identified 92 patients with stage 2–4 CKD caused by primary chronic glomerulonephritis. The patients were followed for 2 years, the changes in NGAL levels in the progressive and non-progressive groups were compared. Results First, the serum NGAL levels of patients with stage 2–4 CKD were significantly increased compared with the control group. Second, based on Pearson correlation analysis, positive correlations existed between NGAL and cystatin C levels and between NGAL and sCr levels. Third, bounded by the progress of renal function, the area under the curve of serum NGAL was 0.872 (95% confidence interval, 0.786–0.933), which suggests a blood NGAL cut-off level of 246 ng/mL (sensitivity 85.19%, specificity 81.54%). Fourth, Kaplan–Meier survival curve analysis showed that the serum NGAL level was closely related to the end-point of renal function in patients with CKD. Fifth, Cox multivariate regression analysis showed that the estimated glomerular filtration rate and blood NGAL are associated with progression of CKD. Conclusion Serum NGAL is an effective biomarker for detecting early-stage renal damage in CKD patients. Serum NGAL was significantly correlated with the severity of renal damage and the progression of renal function deterioration.