The deterioration of chronic leukemia means that the disease progresses to the accelerated stage and the acute stage, which is manifested by fever, fatigue, emaciation, night sweats, enlarged lymph nodes, and so on. 1. The natural course of chronic leukemia includes the chronic phase, accelerated phase and acute phase. The accelerated stage and the acute stage are collectively known as the progressive stage, in which the degree of disease is relatively worse and the patient’s consumptive symptoms increase, manifesting as unexplained fever, fatigue, night sweats, etc. Some patients may also have joint pain, enlarged spleen and enlarged lymph nodes. 2. Acute stage is the end stage of chronic leukemia, which may also present with unexplained fever, further enlargement of spleen with pressure pain, etc. Some patients may also present with symptoms such as bone pain, soft tissue lumps, etc. Anemia and thrombocytopenia may appear in routine blood tests. If the above symptoms occur, it is recommended to go to the hospital as soon as possible, and standardize the treatment under the guidance of the doctor.