Abstract: PUB124
Renal-Limited Atypical Hemolytic Uremic Syndrome: A Case Report
Session Information
Category: Genetic Diseases of the Kidneys
- 1202 Genetic Diseases of the Kidneys: Non-Cystic (Complex and Non-Cystic Monogenic)
Author
- Althuwayb, Mohammed, Aljouf Health Cluster, Sakaka, Al Jowf, Saudi Arabia
Introduction
Renal-limited thrombotic microangiopathy (TMA) without systemic hematologic manifestations is a rare and underrecognized condition, often leading to delayed diagnosis and treatment. CM-HUS is an important underlying etiology in such cases and requires early recognition for targeted complement inhibition therapy.
Case Description
37-year-old woman presented with progressive edema, hematuria, oliguria, and worsening dyspnea.
Labs revealed progressive elevated kidney injury with subnephrotic proteinuria. GN workup were negative. There was no evidence of microangiopathic hemolytic anemia or thrombocytopenia. Initial renal biopsy demonstrated pseudo-crescentic GN, and the patient was treated empirically as ANCA-negative pauci-immune GN using cyclophosphamide alternating with rituximab.
However, renal function continued to deteriorate, necessitating urgent hemodialysis and plasmaphoresis without improvement.
A repeated biopsy revealed features consistent with renal-limited TMA.
Subsequent genetic testing identified a pathogenic mutation in the MCP/CD46 gene, confirming CM-HUS.
The patient was started on the C5 inhibitor Ravulizumab.
Following treatment initiation, dialysis requirements progressively decreased from three sessions weekly to once weekly after six months of therapy, with serum creatinine stabilizing between 178–189 µmol/L.
Discussion
This case highlights the diagnostic challenge of renal-limited aHUS in the absence of systemic hematologic features and emphasizes the importance of repeat kidney biopsy and genetic testing in unexplained progressive kidney injury. Early recognition and initiation of complement inhibitor therapy may significantly improve renal outcomes and reduce dialysis dependence.
widening of the subendothelial space is a classic ultrastructural hallmark of TMA