Urinary podocalyxin positive-element occurs in the early stage of diabetic nephropathy and is correlated with a clinical diagnosis of diabetic nephropathy

Abstract Aims We tested whether urinary podocalyxin-positive element (PCX + EL) can be a marker of early stage of diabetic nephropathy (DN). Methods DN patients (n = 68) and health controls (n = 28) were enrolled in this study. Patients were classified into three groups: normoalbuminuria, microalbuminuria and macroalbuminuria. Urinary PCX + EL, serum cystatin C (Scys C) and serum creatinine (SCr) were quantified, and correlations between urinary PCX + EL and urinary albumin, Scys C and SCr were examined. The comparison of diagnosis efficiency among urinary PCX + EL, Scys C and SCr was made by receiver operating characteristic (ROC) analysis. Results Urinary PCX + EL, Scys C and SCr significantly increased in DN patients compared with controls. Urinary PCX + EL increased significantly in all three patients groups compared with controls. However, the concentration of Scys C and SCr did not increase in normoalbuminuria group. Urinary albumin, Scys C and SCr correlated with urinary PCX + EL. ROC curve analysis indicated that area under the curve (AUC) of urinary PCX + EL (0.966) is higher than that of Scys C (0.857) and SCr (0.726) for discriminating nephropathy between DN patients and controls. Conclusion Urinary PCX + EL may be a noninvasive marker for the early stage of DN.