Abstract: TH-PO0068
Renal-Limited Thrombotic Microangiopathy Without Hemolysis: A Rare Native Kidney Presentation
Session Information
- AKI: Pathogenesis and Disease Mechanisms
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Authors
- Alam, Sreyoshi Fatima, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Keratishvili, Diana, Ascension Saint Francis, Evanston, Illinois, United States
- Galeano, Belinda, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Godby, Richard, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Alexander, Mariam P., Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Bentall, Andrew J., Mayo Clinic Minnesota, Rochester, Minnesota, United States
Introduction
Thrombotic microangiopathy (TMA) involves thrombocytopenia, microangiopathic hemolytic anemia, and organ dysfunction, often causing AKI from endothelial injury. We present a rare case of renal-limited TMA in a native kidney, linked to complement pathway abnormalities, without thrombocytopenia or hemolytic anemia.
Case Description
A 49-year-old man with stable non-compacted cardiomyopathy and previously normal renal function was referred for elevated serum creatinine (1.49 mg/dL). Hemoglobin was 12.5 g/dL, with a urine protein-to-creatinine ratio of 0.22. Intermittent microscopic hematuria (3–10 RBCs/hpf) had been previously noted; urologic workup including cystoscopy and imaging was unremarkable. Anemia evaluation showed normal iron studies, negative GI workup (EGD, colonoscopy), and no hemolysis: normal haptoglobin, reticulocyte count, LDH, peripheral smear, and ADAMTS13 activity. SPEP was negative. Hemoglobin later declined to 11.2 g/dL; C3 was low and C4 was normal. Bone marrow biopsy was unremarkable. There were no recent infections or nephrotoxic medications. Due to persistent renal dysfunction and unrevealing serology, kidney biopsy was done, revealing severe subacute to chronic TMA with mesangial and rare subepithelial deposits and C3-dominant staining. Genetics revealed C3 c.1774C>T (p.Arg592Trp) and MCPggaac/CD46 risk haplotype, both linked to complement-mediated TMA susceptibility. The patient also carried the CFH-H3 risk haplotype but tested negative for C5 variants p.Arg885His and p.Arg885Cys.
Discussion
This case represents a rare instance of primary renal-limited TMA in a native kidney, without classical systemic features. Although renal-limited TMA occurs in certain groups (renal and bone marrow transplant patients, pregnancy and immunotherapy treatment) it remains rare in native kidneys. This underscores the need for a high index of suspicion. Prompt kidney biopsy is essential for accurate diagnosis and guiding treatment.