Kidney Week

Abstract: FR-PO0764

Dual ANCA and Anti-GBM Seropositivity Without Active Glomerulonephritis: A Biopsy-Proven Diagnostic Pitfall

Session Information

• Glomerular Diseases: ANCA Vasculitis, Anti-GBM Disease, and Crescentic GN
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Razaq, Saeed, Crestwood Medical Center, Huntsville, Alabama, United States

Saeed Razaq, MD

• Abro, Sheeraz, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Sheeraz Abro, MD

• Nayab, Khudija, Crestwood Medical Center, Huntsville, Alabama, United States

Khudija Nayab, MD

• Sadiq, Muhammad Hamza, Crestwood Medical Center, Huntsville, Alabama, United States

Muhammad Hamza Sadiq, MD

• Abro, Paras A., The University of Mississippi Medical Center, Jackson, Mississippi, United States

Paras A. Abro, MD, MBBS

• Velagapudi, Ramya Krishna, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Ramya Krishna Velagapudi, MD, FASN

• Habiba, Ume, University of Illinois Chicago, Chicago, Illinois, United States

Ume Habiba, MD

Introduction

Concurrent anti-GBM and ANCA positivity is typically linked to rapidly progressive glomerulonephritis requiring urgent immunosuppression. However, in advanced CKD, positive serology may not indicate active disease, creating a major diagnostic challenge.

Case Description

A 70-year-old woman with stage 4 CKD and diabetes mellitus presented with worsening renal function. Baseline creatinine of 1.5–1.8 mg/dL increased to 2.6–2.8 mg/dL. Urinalysis demonstrated bland sediment with minimal hematuria, and proteinuria measured 1.27 g/day. Serologic evaluation revealed positive anti-GBM antibodies (4.5–5.0) with weak ANCA positivity (MPO 1.3, PR3 0.9), raising concern for dual-positive crescentic glomerulonephritis. Kidney biopsy demonstrated mild diabetic nephropathy (RPS class IIa), 20–30% interstitial fibrosis and tubular atrophy, and 11 of 33 globally sclerosed glomeruli. No crescents, fibrinoid necrosis, or active inflammatory lesions were identified. Immunofluorescence was negative for linear glomerular basement membrane staining and immune complex deposition, excluding active anti-GBM disease and ANCA-associated glomerulonephritis. Given the absence of pathologic evidence of active vasculitis, immunosuppressive therapy was withheld. Renal function subsequently stabilized near a new baseline.

Discussion

This case demonstrates that concurrent anti-GBM and ANCA seropositivity alone does not confirm active glomerulonephritis without supportive clinical, urinary, and histopathologic findings. In advanced CKD, discordant serologies may reflect false-positive or clinically insignificant antibody activity rather than active crescentic disease. Kidney biopsy remains essential for diagnosis and management. Careful clinicopathologic correlation can prevent unnecessary immunosuppression, avoid treatment-related complications, and reduce misclassification of chronic kidney disease as active rapidly progressive glomerulonephritis.

Diabetic nephropathy- Mesangial expansion and arteriolar hyalinosis