Markers Of Renal Tubular Injury In Idiopathic Membranous Nephropathy

Objective:Idiopathic membranous nephropathy（IMN）is a primary glomerular disease and a major cause of adult nephrotic syndrome.Presently,little is known about the capabilities of the urine markers to reflect the severity of IMN.We aimed at establishing whether urinary N-acetyl-β-D-glucosaminidase（NAG）,Retinol binding protein（RBP）,Kidney injury molecule-1（KIM-1）and Neutrophil gelatianse-associated lipocalin（NGAL）are related with renal parameters and the histological grades tubular injury.Methods:165 biopsy-proven IMN patients and 64 healthy controls were enrolled from the nephrology and health screening centres of Shengjing Hospital of China Medical University from 2015 to 2017.The levels of urinary NAG,RBP,KIM-1 and NGAL were determined and compared between patients and healthy subjects,between patients with and without nephrotic syndrome.Their linearity with renal parameters and associations with histological grades of renal tubular injury were also assessed.Results:1.The levels of urinary NAG,RBP,KIM-1 and NGAL in the IMN group were significantly higher than those in the healthy control group.2.The concentration of NAG,KIM-1 and NGAL but not RBP was significantly increased in patients with nephrotic syndrome.3.There was a significant correlation between urinary NAG,KIM-1 and NGAL and other markers of renal impairment in IMN patients.4.All urine markers（except RBP）tended to increase in the patients with moderate and severe grades of histological tubular injury.However,no biomarker was significantly increased among patients with moderate and severe histological grades of tubular injury.5.Apart from serum creatinine and Cys-C,no significant differences in other parameters of renal function were observed between patients with mild histological grade tubular injury and those with moderate-to-severe histological grades.6.The levels of urinary NAG,KIM-1 and NGAL were significantly increased in patients with eGFR below 90ml·min^-1·1.73m^-2.Conclusion:Urinary RBP,NAG,KIM-1 and NGAL levels in patients with idiopathic membranous nephropathy can reflect renal tubular damage,urinary NAG,KIM-1 and NGAL levels were significantly associated with urinary protein（an indicator of prognosis for IMN）;it is speculated that urinary NAG,NGAL,and KIM-1 levels still have the potential to differentiate the severity of tubular damage,especially in patients with significant renal impairment.Although urinary RBP was not significantly associated with other markers of renal function,it can be used as a marker of renal tubular injury in patients with IMN.