False-positive anti-PLA2R ELISA testing in patients with diabetes mellitus

We found the study by Hoxha et al., "False Positivity for PLA2R1 Antibody Measured by ELISA in a Nephrotic Patient With No Membranous Nephropathy," to be of interest.1 We identified 2 similar patients with biopsy-proven diabetic nephropathy with false-positive phospholipase A2 receptor (PLA2R) testing by enzyme-linked immunosorbent assay (ELISA; patients 1 and 2 in Table 1). Within a 5-year period, we had 6 of 5058 serology cases that were PLA2R-positive by ELISA and negative by indirect immunofluorescence assay (0.12%). On subsequent kidney biopsy, 2 had membranous nephropathy and 2 showed nodular diabetic glomerulosclerosis. The remaining 2 patients did not undergo biopsy, including 1 patient with a history of diabetes mellitus and 1 lost to follow-up (Table 1).Patient no.Age, yrSexPLA2R titer, IU/mlKidney biopsy diagnosisTime from serology to biopsy166M85.7Nodular diabetic glomerulosclerosis1 mo2a76M158.1; 182.9Nodular diabetic glomerulosclerosis4 mo3a,b57M471; >1500PLA2R-positive membranous nephropathy2 yr4c78M116.1PLA2R-positive membranous nephropathy2 mo5d71M214.6N/A, did not undergo kidney biopsyN/A672F127.3N/A, did not undergo kidney biopsyN/ATable 1Patient characteristics with positive PLA2R ELISA and negative IFA antibody testingELISA, enzyme-linked immunosorbent assay; F, female; IFA, indirect immunofluorescence assay; M, male; N/A, not available; PLA2R, phospholipase A2 receptor.aPatients 2 and 3 had 2 blood samples tested at different times with the same pattern of results.bPatient 3 was sent in consultation with the manufacturer with the same results.cPatient 4 was tested at a later date (2 months) with positive testing by both IFA and ELISA.dPatient 5 did not undergo kidney biopsy but had a history of poorly controlled diabetes mellitus.Open table in a new tab