Abstract: FR-PO0448
When Serologies Mislead: Dual Positive ANCA and Anti-GBM Antibodies Without Biopsy-Proven Crescentic Glomerulonephritis
Session Information
- AKI: Case Reports - TMA, Vasculitis, Immune-Mediated Injury, and Systemic Disease
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Author
- Yunas, Samia, The University of Mississippi Medical Center, Jackson, Mississippi, United States
Introduction
Dual positivity for antineutrophil cytoplasmic antibodies (ANCA) and anti-glomerular basement membrane (anti-GBM) antibodies is classically associated with rapidly progressive glomerulonephritis and pulmonary-renal syndrome requiring urgent immunosuppressive therapy.However, positive serologies may occur without active glomerulonephritis, creating diagnostic and therapeutic challenges.
Case Description
A 70-year-old woman with CKD stage 4 secondary to diabetes mellitus and cardiorenal disease, HFpEF, hypertrophic obstructive cardiomyopathy status post ICD placement, atrial fibrillation on rivaroxaban, chronic hypoxic respiratory failure on 4 L oxygen, COPD, obesity hypoventilation syndrome, and obstructive sleep apnea was evaluated for worsening renal function after recurrent hospitalizations for respiratory failure.
Baseline creatinine ranged from 1.5–1.8 mg/dL and increased to approximately 2.3 mg/dL outpatient. During hospitalization in January 2026, she developed acute kidney injury with peak creatinine of 4.86 mg/dL. Urinalysis demonstrated hematuria and proteinuria, including approximately 1.3 g/day proteinuria on prior 24-hour urine collection. Differential diagnosis included cardiorenal syndrome, acute tubular necrosis, diabetic kidney disease, and vasculitic glomerulonephritis.
Further serologic evaluation revealed positive ANCA and anti-GBM antibodies, raising concern for pulmonary-renal vasculitis and rapidly progressive glomerulonephritis. Given worsening kidney function and active urinary findings, kidney biopsy was pursued before initiation of immunosuppressive therapy.
Renal biopsy demonstrated mild diabetic nephropathy (RPS class IIa) without evidence of pauci-immune crescentic glomerulonephritis or anti-GBM-mediated disease. Renal function improved with supportive management and diuresis without immunosuppressive therapy.
Discussion
Dual-positive ANCA and anti-GBM serologies typically prompt urgent consideration of aggressive immunosuppression and plasma exchange. This case highlights clinicopathologic discordance in a medically complex patient whose presentation strongly suggested pulmonary-renal vasculitis, yet biopsy demonstrated only diabetic nephropathy. Reliance on serologies alone could have exposed this patient to unnecessary high-risk immunosuppressive therapy.