High white blood cells in routine blood tests are commonly due to two reasons: one, the presence of an infection. Second, the presence of certain blood disorders. Leukocytes are differentiated from granulocytes in the bone marrow and are the most important immune cells in the body, their main function is to engulf bacteria and defend against diseases. The white blood cells produced by the bone marrow are not functional, and the value of white blood cells in the routine blood test is increased, but they do not work, which can easily lead to infections in patients with leukemia, often accompanied by a decrease in red blood cells and platelets, and other tests such as bone marrow biopsy can also see sick cells.