Lymphocytes 6.7% indicates a decrease in the percentage of lymphocytes. Possible causes include drug-induced, radiation damage, and T-lymphocyte immunodeficiency disease, which is still dangerous. 1. Drug-induced: such as adrenal hormones, anti-tumor drugs (cytarabine, anti-lymphocyte globulin) and so on. Long-term use of adrenal hormones will not only cause a decrease in lymphocytes, reduce the body’s immunity, but also cause osteoporosis. Anti-tumor drugs can kill normal cells, but also inhibit bone marrow hematopoiesis, causing a decrease in whole blood cells, which can easily lead to infections, bleeding and so on. 2. Radiation damage: radiation can damage the normal cells of the body, but also can trigger cell mutation. The probability of leukemia will increase if you work under the environment of radiation exposure for a long time. 3. In addition to the above, low lymphocyte percentage may also be caused by T-lymphocyte immunodeficiency disease, gammaglobulin deficiency and so on. The above test results alone cannot accurately determine the cause of the disease, and it is necessary to combine the characteristics of the medical history and other test results to make an accurate judgment. It is recommended to clarify the cause of the disease under the guidance of a doctor, and to carry out regular treatment in a timely manner.