·To examine the role of blood lipoprotein phospholipase A2 (Lp-PLA2) and neutrophil gelatinase-associated lipocalin (NGAL) in the diagnosis of early diabetic nephropathy (DN).Methods
·A total of 219 participants with type 2 diabetes mellitus diagnosed in the Department of Endocrinology of Taizhou People's Hospital from January 2017 to April 2019 were enrolled. The levels of Lp-PLA2, NGAL, urinary albumin excretion rate (UAER), blood urea nitrogen (BUN), serum creatinine (Scr), uric acid (UA), cystatin C (Cys-C), blood glucose, and blood lipid in all participants were detected. All diabetics were classified into three groups based on UAER: normal albuminuria (NA) group (n=75), microalbuminuria (MA) group (n=73) and heavy albuminuria (HA) group (n=71). The MA group and HA group were classified as DN group.The differences of the above indicators among each group were compared, and the relationship of Lp-PLA2, NGAL and DN were analyzed by Pearson linear correlation, multiple linear regression, Logistic regression and receiver operator characteristic curve.Results
·Compared with the NA group and MA group, the levels of Lp-PLA2, NGAL, BUN, SCr, UA and Cys-C in the HA group were significantly increased (P<0.05). However, compared with the NA group, only Lp-PLA2 and NGAL levels in the MA group were significantly increased (P<0.05). Correlation analysis found the Lp-PLA2 and NGAL were positively correlated with UAER (r=0.397, r=0.511), BUN (r=0.274, r=0.411), SCr (r=0.237, r=0.419), and Cys-C (r=0.278, r=0.436) (all P=0.000), whereas negatively correlated with the estimate glomerular filtration rate (r=-0.170, r=-0.366; P=0.013, P=0.000). Multiple linear regression analysis showed that Lp-PLA2, NGAL and Cys-C were related factors of UAER. Binary Logistic regression analysis found that Lp-PLA2 and NGAL were still risk factors of kidney injury in DN after adjustment for blood pressure, lipids, glycosylated hemoglobin and duration of diabetes (OR=1.012, OR=1.024; P=0.009, P=0.000). The area under the curve (AUC) of Lp-PLA2, NGAL and their combination in diagnosis of DN were 0.700, 0.855 and 0.871. NGAL demonstrated high sensitivity (81.2%) and specificity (80.0%). Lp-PLA2- and NGAL-combined detection had the highest diagnostic efficiency (AUC=0.871).Conclusion
·Both blood Lp-PLA2 and NGAL levels are closely associated with the renal damage in participants with DN. As independent risk factors of DN, Lp-PLA2 and NGAL have been highly expressed in early DN, which could better reflect the occurrence of early DN, compared with traditional renal function indicators. Lp-PLA2- and NGAL-combined detection could demonstrate its maximum diagnostic efficacy, providing a new method for the diagnosis of early renal injury.