The precursors of leukemia include bone swelling and pain, fatigue, skin ecchymosis, active bleeding from the gums or nasal cavity, and fever. 1. Leukemia patients with abnormally active proliferation of leukemia cells in the bone marrow may have symptoms such as bone soreness and distension, but the white blood cells have not yet been released into the peripheral blood, and there is no indication of a markedly elevated white blood cell count yet. When the normal hematopoietic function of bone marrow is significantly inhibited, the production of red blood cells and platelets decreases, resulting in anemia and reduced platelet count. 2. With the gradual aggravation of anemia, patients may have symptoms of anemia such as dizziness and fatigue; when the platelet count is severely reduced, spontaneous petechiae and ecchymosis or small bright-red hemorrhages can be seen on the skin, and unexplained bleeding from the gums and the nasal cavity can occur. 3. The normal white blood cell production in the bone marrow of leukemia patients is inhibited, the immunity of the body decreases sharply, and lung infections, urinary tract infections and other diseases are easy to occur, and fever will also appear when there is a lack of granulocytes. When the above symptoms occur, it is recommended to consult the hematology department in time. If the possibility of leukemia is considered, bone marrow aspiration and biopsy should be performed to make a clear diagnosis, and once the diagnosis is clear, individualized treatment plan should be formulated by specialists for active treatment immediately.