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.

Keywords: Diabetic nephropathy; Flow cytometry; Podocalyxin; Podocyte.