Utility of serum anti-phospholipase A2 receptor antibody as a biomarker in membranous nephropathy: An experience from a tertiary care center of Eastern India

Background: Membranous nephropathy (MN) is a pattern of glomerular injury. Exact categorization into primary membranous nephropathy (PMN) or secondary membranous nephropathy (SMN) is essential for treatment. An endogenous podocyte antigen, M-type phospholipase A2 receptor (PLA2R) has been discovered to be involved in the pathogenesis of PMN. Aims and Objectives: In this article, we aimed to analyze renal tissue PLA2R and serum anti-PLA2R antibodies in MN cases and determined the diagnostic utility. Materials and Methods: The study was of prospective type carried out from March 2019 to August 2020. Analysis of cases of MN was performed with PLA2R paraffin immunoflourescence and serum anti-PLA2R antibody ELISA. Results: Overall sensitivity, specificity, PPV, and NPV of serum anti-PLA2R ELISA for PMN was 91.3%, 80%, 75%, and 93.3%, respectively, and of tissue PLA2R staining for PMN was 91.67%, 81.08%, 75.86%, and 93.75%, respectively. There was strong concordance between two methods. In the patients that were followed up, we found baseline serum anti-PLA2R antibody was less in complete remission group than that in non-remission group and the reduction in serum anti-PLA2R antibody was more in complete remission group than that in non-remission group. Conclusion: Routine light and immunofluorescence examination are incapable of giving exact categorical opinion regarding PMN and SMN. Serum anti-PLA2R antibody detection and renal tissue PLA2R analysis are sensitive and specific in detecting PMN. Baseline serum anti-PLA2R antibody and anti-PLA2R antibody quantification trends are related to prognosis of PMN. So they can be incorporated as additional biomarker.