High neutrophils and low lymphocyte percentage in routine blood tests may be caused by physiological reasons, such as late pregnancy, strenuous exercise, high temperature or severe cold, etc.; they may also be caused by pathological reasons, such as bacterial infections and leukemia. 1. Physiological reasons: in the late stage of pregnancy, strenuous exercise, high temperature or severe cold, blood circulation is accelerated, the body produces a stress reaction, a transient stimulus to increase the release of neutrophils, resulting in high values, low lymphocytes, usually after eliminating the influencing factors can be restored to normal. 2. Pathologic causes (1) During bacterial infection, neutrophils phagocytose bacteria under the action of chemokines and inflammatory factors to reduce their damage to the organism and avoid the spread of infection; (2) Most leukemia types pathologically generate a large number of neutrophils in the hematopoietic tissues within the bone marrow, which are released into the peripheral blood, resulting in an elevation of neutrophils and a decrease in lymphocytes. (3) A large number of erythrocytes are destroyed during severe tissue injury, and the stress response mobilizes the bone marrow storage pool to release neutrophils into the blood circulation. Neutrophils can phagocytose destroyed erythrocytes and strengthen the body’s defenses, and routine blood tests will also show high neutrophils and low lymphocytes. Routine blood test neutrophils high lymphocyte percentage is low, it is recommended to be interpreted by a professional physician, if there is any discomfort, it is recommended to consult a doctor in a timely manner.