Membranous nephropathy and nonsteroidal anti-inflammatory agents

Membranous nephropathy presents clinically as nephrotic syndrome, with subepithelial immune complex deposits seen on biopsy. Historically, in about three-quarters of membranous cases, no obvious etiologic agent or condition can be identified. More recently, serum antibodies to the phospholipase A ₂ receptor have been discovered in many patients with primary/idiopathic membranous nephropathy. About one-quarter of patients have membranous nephropathy as a manifestation of another systemic disorder, such as autoimmune conditions, infection, malignancy, toxin exposure, or drugs (classically gold or penicillamine). In this report, we present a case of recurrent nephrotic syndrome with biopsy-proven membranous nephropathy closely associated with use of the nonsteroidal anti-inflammatory drugs (NSAIDs) naproxen and piroxicam. Characterization of the immunoglobulin G (IgG) subclass profile of the deposits showed abundant IgG1, weak IgG4, and positive staining for phospholipase A₂ receptor. This case serves to highlight membranous nephropathy as an under-recognized renal complication of NSAID use. Other kidney effects of NSAIDs, such as hemodynamic compromise, interstitial nephritis, and minimal change disease, are more broadly recognized.