There are three main precursors to leukemia in the elderly: bleeding, infection, and anemia. Elderly leukemia causes a decrease in platelets, normal white blood cells and red blood cells, which leads to the typical symptoms of bleeding, infection and anemia respectively. 1. Bleeding can cause petechiae and ecchymosis on the skin and mucous membranes, as well as gastrointestinal bleeding such as vomiting blood and blood in the stool, and urinary tract bleeding such as hematuria. 2. Infection mainly manifests as respiratory tract infection, but also can be urinary tract infection, the patient usually appears fever with chills. 3. A part of patients with anemia as the main manifestation, such as long-term chest tightness and shortness of breath, loss of appetite, and so on, and even lead to anemic heart disease. If these symptoms occur, suspected leukemia, should go to the hospital in a timely manner, under the guidance of physicians to clarify the diagnosis and identify the causes.