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Kidney Week

Abstract: FR-OR081

Non-Invasive Diagnosis of Primary Membranous Nephropathy using Phospholipase A2 Receptor Antibodies

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Bobart, Shane A., Mayo Clinic, Rochester, Minnesota, United States
  • De Vriese, An S., AZ Sint-Jan , Bruges, Bruges, Belgium
  • Zand, Ladan, Mayo Clinic, Rochester, Minnesota, United States
  • Sethi, Sanjeev, Mayo Clinic, Rochester, Minnesota, United States
  • Giesen, Callen D., Mayo Clinic, Rochester, Minnesota, United States
  • Lieske, John C., Mayo Clinic, Rochester, Minnesota, United States
  • Fervenza, Fernando C., Mayo Clinic, Rochester, Minnesota, United States
Background

Kidney biopsy is the current gold standard to diagnose membranous nephropathy (MN). Approximately 70-80% of patients with primary MN have circulating anti-PLA2R antibodies. We hypothesized that PLA2R antibody testing without the need for a biopsy is a valid strategy to make a non-invasive diagnosis of MN in the setting of preserved renal function and negative work up for secondary causes such as autoimmunity, malignancy, medications and paraproteinemias.

Methods

The medical records of all Mayo Clinic patients with positive serum PLA2R antibody tests between July 2015 and December 2017 were reviewed.

Results

A total of 1065 PLA2R tests were ordered on 675 unique patients. Of these, 113 had a positive PLA2R antibody test, of which 105 had native renal biopsies performed. The primary diagnosis in all biopsies was MN. Eighty-four patients had a negative work up for secondary causes of MN. Fifty of the 84 patients had preserved renal function (eGFR >60 ml/min/1.73m2). In none of these 50 patients, kidney biopsies provided significant information that altered diagnosis or management. Among the 34 patients with eGFR <60 ml/min/1.73m2, additional findings that altered the treatment plan included acute interstitial nephritis (n=1), superimposed diabetic nephropathy (n=1) and cellular crescents (n=1). Potential secondary causes were identified in 21 cases (positive ANA test = 4, malignancy = 9, NSAID = 3, monoclonal protein = 5). A detailed review of the clinical data revealed that these were co-existing findings and not true secondary MN.

Conclusion

In patients with preserved renal function and no evidence of secondary causes, a positive PLA2R test confirms the diagnosis of MN. A kidney biopsy does not add significant data in this context.