Severe AKI Due to Renal-Limited Anti-GBM Disease with Thrombotic Microangiopathy

Introduction: Anti-glomerular basement membrane (Anti-GBM) disease is a rare, rapidly progressive vasculitis characterized by autoimmune damage to the basement membrane of the lungs and kidneys. It often presents with pulmonary hemorrhage and acute kidney injury (AKI). A unique subset is renal-limited anti-GBM disease, where there is no pulmonary involvement. In this case report, we describe a rare form of renal-limited anti-GBM disease complicated by thrombotic microangiopathy (TMA). Case Description: A 62-year-old woman with a history of hypertension, hyperlipidemia, and coronary artery disease presented with fever, chest pain, leg edema, and decreased urine output. On physical exam, she was found to be volume overloaded. Labs revealed severe AKI with creatinine 15 mg/dL from a baseline of 0.75mg/dl, BUN 120 mg/dL, potassium 7 mEq/L, pyuria, microscopic hematuria, proteinuria(300 mg/dl), and low complement C3 level of 75 mg/dl and C4 of 19 mg/dl. ADAMTS13 activity was low (0.51 IU/ml), with evidence of microangiopathic hemolysis on blood smear. Kidney ultrasound was unremarkable. Anti-GBM antibody was markedly elevated at 600 IU/mL. A kidney biopsy revealed anti-GBM disease with extensive glomerular necrosis, crescent formation, and features of TMA. She developed respiratory failure requiring intubation. A bronchoscopy ruled out pulmonary hemorrhage. She was started on hemodialysis and treated with glucocorticoids, plasmapheresis, and oral cyclophosphamide. Despite treatment, the patient did not have any renal recovery. Discussion: This case highlights the need to consider anti-GBM disease even in the absence of pulmonary hemorrhage and to recognize atypical complications such as TMA, which may signal a more aggressive disease course and influence treatment decisions. Although TMA is an uncommon manifestation of anti-GBM disease, its presence suggests an overactivation of the complement system. This patient presented with a severe AKI requiring dialysis, a common initial manifestation of anti-GBM disease. Despite timely interventions, the prognosis in such cases remains guarded, particularly when kidney biopsy reveals extensive crescent formation.