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Abstract: PO1901

Noninvasive Diagnosis of Primary Membranous Nephropathy Using Anti-Phospholipase A2 Receptor (PLA2R) Antibodies: A Validation Study

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Bobart, Shane A., Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Tehranian, Shahrzad, Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Andrades Gómez, Cristina, Hospital Universitario Virgen del Rocio, Sevilla, Andalucía, Spain
  • Sethi, Sanjeev, Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Giesen, Callen D., Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • Lieske, John C., Mayo Clinic Minnesota, Rochester, Minnesota, United States
  • De Vriese, An S., AZ Sint-Jan Brugge-Oostende AV, Brugge, Belgium
  • Fervenza, Fernando C., Mayo Clinic Minnesota, 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 sought to validate our previous work showing that in a proteinuric patient with preserved renal function (eGFR >60ml/min/1.73m2) and no associated conditions (e.g. autoimmunity, malignancy, infection, drugs, paraproteinemia) a positive anti-PLA2R antibody test by simultaneous ELISA and IFA, is a valid strategy to make a non-invasive diagnosis of primary MN (Bobart et al. KI 2019; 95: 429-438).

Methods

The medical records of all Mayo Clinic patients with positive serum anti-PLA2R antibody tests by both ELISA and IFA between July 2018 and April 2020 were reviewed.

Results

A total of 1522 anti-PLA2R antibody tests were ordered in 1112 unique patients, yielding 128 positive results. We excluded previously reported patients (n=33), renal transplant recipients (n=5), no biopsy available (n=18), and pediatric cases (n=2). In all 70 remaining patients, the primary biopsy diagnosis was MN. Associated disease was identified in 28 cases (autoimmunity = 10, malignancy = 6, NSAID = 4, Hepatitis = 3, monoclonal protein = 5). Of the 42 patients with negative work up for secondary causes, 32 (76%) had preserved renal function. One patient had fibrin thrombi and neutrophils in the capillary loops, and one patient had 1 glomerulus with focal glomeruar basement membrane duplication. Neither of these findings altered diagnosis or management. Among the 10 patients with eGFR <60 ml/min/1.73m2, additional findings that altered the treatment plan included acute interstitial nephritis (n=1) and superimposed diabetic nephropathy (n=1).

Conclusion

The study extends our previous observations that in patients with preserved renal function and no evidence of secondary causes or diabetes, a positive PLA2R test by simultaneous ELISA and IFA confirms the diagnosis of MN.