MON-017 SENSITIVITY AND SPECIFICITY OF SERUM PLA2 RECEPTOR ANTIBODIES IN DIAGNOSIS OF PRIMARY MEMBRANOUS NEPHROPATHY

Abstract

Membranous nephropathy is a common cause of Nephrotic syndrome in adults and often requires a kidney biopsy to make a diagnosis, recent past there is a debate whether PLA2R antibodies will help in making a diagnosis of primary MGN without renal biopsy We carried out a prospective to Study to determine the association between serum anti-PLA2Rantibody and glomerular staining for PLA2R in Membranous Nephropathy Study design : Prospective observational, study duration: May 2016 to May 2018 Inclusion criteria: Adult Nephrotic syndrome those who are aged above 18 years undergoing kidney biopsy at our hospital Material & Methods: Serum for anti-PLA2R antibody was sent prior to kidney biopsy in all subjects. The serum anti- PLA2R antibodies was tested by Indirect immunofluorescence staining using validated commercial kits(Euroimmun). The kidney biopsy samples were subjected to light microscopy,immunofluorescence testing for the panel of antibodies as per standard protocol. Subsequently PLA2R staining was done as per standard protocol in those subjectswho showed features of membranous nephropathy In our study 13 out of 58 subjects who presented with nephrotic syndrome had positive serum anti-PLA2R Ab in samples analysed at presentation and prior tokidney biopsy. This account for 22.4% of the study subjects, while 45(77.6 %) subjects were negative for the same. Of the 13 subjects with positve serum anti-PLA2R Ab, 12 subjects had light microscopy and immunofluorescence findings ofMN on kidney biopsy. One subject who had FSGS-NOS type on kidney biopsyshowed weak positive serum anti-PLA2R antibody. Among the other 45 subjects who did not have serum anti-PLA2R antibody, there wasan additional 16 subjects who were diagnosed with primary MN and 1 with secondaryMN by kidney biopsy. This gives a Sensitivity of 41.38%, Specificity of 96.6%,Positive Predictive Value of 92.31%, Negative Predictive Value of 62.22% anddiagnostic accuracy of 68.97% for the test for diagnosis of MN by anti-PLA2Rantibody Statistical analysis by Cohen's kappa test showed a low agreement betweenserum anti-PLA2R Ab and Kidney biopsy was 0.3793 (0.1647 - 0.594). In our study the sensitivity and specificity of PLA2R antibodies in predicting adiagnosis of primary membranous nephropathy (pMN) 42.8% and 96.6% respectively Glomerular PLA2R staining had a sensitivity of 82.8% for diagnosis of MN and 85.5% for diagnosis of primary MN.