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Atypical hemolytic uremic syndrome (aHUS) is an entity characterized by microangiopathic hemolytic anemia, thrombocytopenia, and multisystemic organ dysfunction. Histologically, it is characterized by endothelial damage, widening and edema of the subendothelial space due to cell lysis material, and the subsequent presence of thrombi obstructing capillary lumen. It presents with a prevalence of 0.5 -1% per million population and approximately 50% of subjects develop end-stage kidney disease.
Prospective study performed at the British Hospital of Buenos Aires including clinical data, laboratory results, genetic studies and the respective treatment from time of diagnosis to the present time.
We report 10 cases of aHUS from 2014 to 2024, with 60% (n=6) of female gender, median age 40.7(18–64). At the time of diagnosis 30% (n=3) of patients presented systemic infections; 20% (n=2) with pregnancy; 20% (n=2) in the post-transplant period and 30% (n=3) with nephritic syndrome. All presented low haptoglobin levels, hypocomplementemia, thrombocytopenia, ADAMTS13 within normal limits, Shiga toxin stool test were negative, microangiopathy hemolytic anemia and renal damage, with 70% (n=7) requiring acute dialysis. All patients had hypertension. A renal biopsy was performed in all patients with a diagnosis of thrombotic microangiopathy (TMA) in 90% of them.
Initial approach consisted on plasmapheresis with plasma replacement and corticosteroid. Eculizumab was started as per availability in all cases. Currently 100% continue with eculizumab therapy. Mortality rate: 30%(n=3) and 20% (n=2) continue on chronic dialysis and 2 received a kidney transplant. In 50% (n= 5) of cases genetic mutations were identified: MCP; CFH; CFHR3 and CFHR1
aHUS is a rare syndrome cause by dysregulation with over-activation of the alternative complement pathway. The diagnosis is made on clinical grounds and must lead to prompt therapeutic intervention. An early diagnosis leads to patient’s stabilization and eculizumab is a safe therapy that’s leads to plasmapheresis discontinuation.