HP and congenital thrombotic thrombocytopenic purpura: aHUS is a rare, complex, multifactorial disease characterized by microangiopathic hemolytic anemia (hemoglobin <10 mg/dL; negative direct Coombs Test; elevated LDH; decreased haptoglobin; reticulocytosis; presence of schistocytes), thrombocytopenia (platelets <150 × 109/L or decrease >25 % from baseline) and AKI [1, 2, 7, 8].