Background Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker of acute kidney injury. cohort are offered in Table 1. Mean age of the patients (11 females and 20 males [ratio, 1:2]) was 62.410.2 years. Mean serum creatinine was 1.660.82 mg/dL with a mean GFR of 49.317.5 mL/min/1.73 m2 (range, 13.1 to 78.3). The mean urinary NGAL level of the CKD patients was significantly higher than that measured in healthy controls (96.0 [2.7 to 975.2] ng/mL vs. 18.8 [1.3 to 81.9] ng/mL, P=0.02) and GFR was lower than those in healthy controls (49.3 [13.1 to 78.3] mL/min/1.73 m2 vs. 85.6 [72 to 106.7] mL/min/1.73 m2, P<0.0001) (Fig. 1). Fig. 1 Urinary neutrophil gelatinase-associated lipocalin (NGAL) levels and glomerular filtration rate (GFR) in patients and healthy populations. (A) NGAL levels: 18.8 (1.3 to 81.9) ng/mL vs. 96.0 (2.7 to 975.2) ng/mL (P=0.02). (B) GFR: 49.3 (13.1 to 78.3) mL/min/1.73 … Table 1 Demographic data of 31 patients and Polygalaxanthone III IC50 36 healthy individuals Correlation between GFR and urinary NGAL levels The correlation analyses between GFR and urinary NGAL levels in CKD patients are offered in Fig. 2. The urinary NGAL level showed a significant inverse correlation with GFR in CKD patients (r=-0.5634, P<0.0001). Fig. 2 Correlation analysis between glomerular filtration rate (GFR) and urinary Polygalaxanthone III IC50 neutrophil gelatinase-associated lipocalin (NGAL) in chronic kidney disease patients (r=-0.5634, P<0.0001). Correlation between Polygalaxanthone III IC50 urinary protein level and urinary NGAL and GFR The correlation analyses between urinary protein and urinary NGAL levels in CKD patients are offered in Fig. 3. The correlation between urinary protein and urinary NGAL levels and GFR in patients were as follows: urine protein and urinary NGAL (r=0.3009, P=0.0256), urine protein and GFR (r=-0.6245, P<0.0001), urine albumin and urinary NGAL (r=0.1794, P=0.2275), and urine albumin and GFR (r=-0.5190, P=0.0002). The urinary NGAL level was significantly correlated with the amount of urinary protein excretion in CKD patients. GFR, like urinary NGAL, also showed a strong correlation with the extent of urinary protein, including albumin, but the level of correlation with GFR was even greater in CKD patients in our study. In addition, only GFR showed a negative correlation with UACR (r=0.5497, P=0.0001). Urinary NGAL, however, was not correlated with UACR. Fig. 3 Correlation analyses for urine Polygalaxanthone III IC50 protein and urinary neutrophil gelatinase-associated lipocalin (NGAL) levels and glomerular filtration rate (GFR) in chronic kidney disease patients. Correlations were analyzed between urinary protein level and urinary NGAL … Correlation between the age, sex, and GFR and urinary NGAL in the control group In the analyses with the control subjects, no significant correlation was observed between urinary NGAL levels and other variables (Fig. 4). Fig. 4 Correlation between age (A) (r=-0.1488, P=0.3866), sex (B) (P=0.1823), and glomerular filtration rate (GFR) (C) (r=-0.2621, P=0.1226) and urinary neutrophil gelatinase-associated lipocalin (NGAL) in healthy populations. Conversation Many clinical studies have exhibited the power of NGAL as a specific, sensitive, and early predictor of AKI [3-7]. In CKD, there are also many reports suggesting that NGAL is also a novel, impartial marker of disease progression that provides a good reflection of the severity of renal disease. A variety of clinical settings have been examined, including cardiac surgery, contrast administration, septic shock, intensive care models, the emergency department, and even renal transplantation [7,14-22]. In one study of CKD patients secondary to renal dysplasia, obstructive uropathy, and glomerular and cystic diseases, plasma NGAL concentrations were inversely associated with GFR . Another study in subjects with CKD (due to chronic glomerulonephritis) showed that mean urinary NGAL concentrations were higher in CKD patients (378.28111.13 g/L vs. 7.383.26 g/L in controls, P=0.01). Furthermore, urinary NGAL concentrations were significantly correlated with GFR (r=-0.528, P=0.04) and proteinuria (r=0.294, P=0.01) . In a study of 80 non-diabetic patients with CKD stages 2 to 4, 80 kidney transplant recipients, and 32 healthy control subjects, the investigators found that serum NGAL values were significantly higher in kidney allograft recipients and patients with CKD compared with healthy controls. NGAL PJS rose gradually, reaching the highest value in advanced CKD . In addition, Bolignano et al. .