Etanercept

Abstract

Membranous nephropathy: case report An 80-year-old man developed membranous nephropathy during treatment with etanercept for seropositive rheumatoid arthritis. The man was diagnosed with seropositive rheumatoid arthritis at the age of 35 years and maintained in clinical remission on methotrexate treatment until 2017. Thereafter, his rheumatoid arthritis started to flare and his treatment was switched to sulfasalazine. However, because of ongoing high disease activity, his therapy was changed to etanercept [Benepali; route and dosage not stated] along with methotrexate in December 2018. Eventually, his rheumatoid arthritis was controlled with diseasemodifying anti-rheumatic drugs (DMARDs) with normal blood count, and liver and renal profile (estimated glomerular filtration rate (eGFR)) for 7 months of treatment therapy. In June 2019, 8 months after the initiation of etanercept, a drop in his eGFR was noted as 46. Therefore, his methotrexate therapy was stopped. In July 2019, regardless of discontinuation of methotrexate, his eGFR was decreased to 28. Therefore, the man’s etanercept therapy was discontinued. Subsequently, he was referred to renal physicians. On presentation, he was normotensive without dependent oedema. A renal tract ultrasound scan demonstrated normal appearing kidneys. Urine dipstick revealed 2+ blood and 2+ protein and an elevation in urine protein: creatinine ratio along with decreased serum albumin. Serum anti-phospholipase A2 receptor antibody, serum electrophoresis, and HIV and hepatitis PCRs were found to be negative. Renal biopsy showed stage I to II membranous nephropathy with mild focal segmental glomerulosclerosis. Based on presenting symptoms and investigational findings, a diagnosis of membranous nephropathy secondary to etanercept was made. Following the discontinuation of etanercept therapy, an improvement in his renal function and proteinuria were noted, which was found to be normal a few months later.