Q. A 4-year-old boy is brought to the ER by his parents because of yellowing of his eyes, fatigue, and decreased urinary output. The mother mentions that the patient had bloody diarrhea 10 days ago. On clinical examination, There are petechiae and purpura over his trunk and lower extremities. On blood smear, there are schistocytes. If you know that creatinine levels are increased and there is normal PT and PTT, what is the cause of these symptoms?