C3 Glomerulopathies: Navigating Diagnostic and Therapeutic Challenges in Anticoagulated Patients

Introduction: C3 glomerulopathies are rare kidney disorders marked by dysregulated complement pathways, leading to C3 deposition in the glomeruli. They're classified into Dense Deposit Disease (DDD) and C3 glomerulonephritis (C3GN). Case Description: A 56-year-old male with history of hypertension, mechanical aortic valve replacement on anticoagulation and autoimmune hemolytic anemia, seen initially for elevated creatinine at 2.4, in January 2023, attributed to pigment nephropathy or Coumadin-associated nephropathy given presence of microscopic hematuria; despite considering glomerular issues, a biopsy was not pursued given overall stable kidney function and anticoagulation. A year later he experienced worsening kidney function, with serum creatinine of 4.1 mg/dL, leading to hospitalization. Laboratory tests revealed persistent proteinuria, hematuria, and low C3 and C4 level. Kidney biopsy showed mesangial and capillary loop C3 deposition, ultrastructural examination showed very rare electro-dense deposits within the mesangium, no deposits within the glomerular basement membrane. Biopsy was complicated by perinephric hematoma requiring transfusion. Treatment with Prednisone and mycophenolate mofetil (MMF) was initiated, and the patient was referred to a glomerular disease center. Discussion: This case underscores the challenges in treating glomerular diseases, particularly in anticoagulated patients, requiring a thorough, individualized approach. Symptoms include varying degrees of proteinuria, hematuria, low C3 levels, and kidney dysfunction with hypertension. Diagnosis relies on kidney biopsy, with immunofluorescence and electron microscopy aiding differentiation. Further tests may be needed for causative factors and tailor treatment. Treatment, often comprising MMF and glucocorticoids, alongside supportive care.