In the differential diagnosis of thrombotic microangiopathy, HUS was eliminated due to the absence of Shiga toxin-induced infection and bloody diarrhea; disseminated intravascular coagulation (DIC) was excluded based on normal PT, aPTT, and fibrinogen levels; and thrombotic thrombocytopenic purpura (TTP) was excluded due to the negative ADAMTS13 test; based on the laboratory and clinical findings, the patient was diagnosed with aHUS. This evidence concerns the gene ADAMTS13 and thrombotic thrombocytopenic purpura.