Anti-GBM/ANCA double-positive crescentic nephritis in an elderly patient presenting with heart failure-like symptoms

Rationale: Anti-glomerular basement membrane (anti-GBM) antibody disease and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis represent the 2 leading causes of rapidly progressive glomerulonephritis (RPGN). The coexistence of these conditions is rare, typically progresses rapidly, and has a poor prognosis. Elderly patients often present with nonspecific systemic symptoms, increasing the likelihood of misdiagnosis and treatment delay. Patient concerns: A 74-year-old woman presented with a one-month history of intermittent shortness of breath, worsening progressively over ten days, accompanied by nausea and vomiting. She denied hemoptysis, gross hematuria, rash, or arthralgia. Diagnoses: Initial assessment suggested heart failure. However, laboratory results revealed severe renal impairment (creatinine: 1025.99 μmol/L). Renal biopsy demonstrated crescent formation in over 80% of glomeruli, with immunofluorescence showing linear immunoglobulin G deposits along glomerular capillary loops. Serological testing revealed markedly elevated anti-GBM antibody (>400 RU/mL) and MPO-ANCA (108.4 RU/mL) levels, together with a perinuclear ANCA (P-ANCA) pattern on indirect immunofluorescence, supporting the diagnosis of anti-GBM glomerulonephritis with concomitant MPO-ANCA positivity. Interventions: Treatment included methylprednisolone pulse therapy, cyclophosphamide, and 3 plasma exchange sessions. Additional supportive measures comprised hemodialysis, antihypertensive therapy, and management of renal anemia. Outcomes: Although the patient’s uremic symptoms improved markedly, renal function did not recover. She was discharged on hemodialysis and was subsequently transitioned to maintenance peritoneal dialysis. By January 2026, the anti-GBM antibody level had decreased markedly to 4.27 RU/mL, below the positive cutoff, and MPO-ANCA had also become negative. At the last follow-up in April 2026, the patient remained dialysis-dependent and experienced recurrent hospitalizations for pneumonia, heart failure, and acute pancreatitis. Lessons: This case emphasizes that elderly patients with anti-GBM/ANCA double-positive crescentic glomerulonephritis may initially present with nonspecific symptoms, increasing the risk of incorrect diagnosis. Although combination therapy resulted in symptomatic improvement and serological remission, renal function failed to recover and dialysis dependence persisted. Screening for anti-GBM antibody and ANCA should therefore be considered in patients with unexplained rapidly progressive deterioration of kidney function or active urinary sediment, and renal biopsy should be performed promptly when clinically indicated.