Urinary Podocyte Loss is Associated With Treatment Response in Patients With Primary Nephrotic Syndrome

The disease course of primary nephrotic syndrome (PNS) is highly variable, and is difficult to predict at onset. PNS is characterized by podocyte injury and loss. We hypothesized that measurement of urinary podocyte loss is associated with treatment response in patients with PNS.

We included 21 controls, and 59 patients with PNS (minimal change disease [MCD], n =8; focal segmental glomerulosclerosis [FSGS], n = 9; membranous nephropathy [MN]. n = 42). MCD and FSGS were considered manifestations of the same disease entity, and analyzed as one group. Patients' baseline clinical and follow-up data were recorded. Urinary sediments were collected and stained for podocyte-specific markers, and analyzed using fluorescence-activated cell sorting (FACS).

In patients with MCD/FSGS, the respective partial and complete remission rates were 24% and 59% during a median follow-up of 12.9 months, and all patients received immunosuppressive treatment. In patients with MN, the respective partial and complete remission rates were 64% and 19% during a median follow-up of 15.5 month, and the majority of patients received immunosuppressive treatment. Patients with PNS had elevated levels of podocyturia when compared with controls, and repeat measurements revealed that podocyturia follows proteinuria course over time, normalizing following complete proteinuria remission. In treatment-responsive immunosuppresive-treated patients with MCD/FSGS, podocyturia at baseline significantly differentiated between early and late treatment responders at 4 weeks, contrary to proteinuria and serum albumin. In symptomatically treated patients with MN, low levels of podocyturia at baseline were associated with spontaneous remission.

Patients with PNS have increased podocyturia compared with healthy individuals. Quantitative detection of podocyturia may have prognostic relevance in patients with PNS.