The causes of high white blood cells can be seen in the following: 1. Infections, bacterial and viral infections may cause elevated white blood cell counts afterwards. After giving active anti-infection treatment, the white blood cell count can be reduced to positive after the infection is controlled. 2, blood system diseases, such as acute leukemia, chronic leukemia, myelodysplastic syndrome, true erythrocytosis, primary thrombocytosis can cause elevated white blood cell count, in order to make a clear diagnosis, bone marrow aspiration, flow cytology, genetic testing and other tests are needed to confirm the diagnosis. 3, some Patients treated with glucocorticoids for a long time, such as patients with rheumatoid arthritis, systemic lupus erythematosus, dry syndrome and other connective tissue diseases, need to use hormone therapy for a long time. This can also cause high white blood cell counts, which can be reduced to normal by reducing or stopping the medication.