For adults, 13 units of white blood cells in peripheral blood is a significantly elevated white blood cell count. Whether 13 units of leukocytes is serious depends on the cause of the elevated leukocytes. For example, if a patient presents with 13 units of leukocytes along with symptoms of respiratory tract infection such as fever, cough, sputum and chest tightness, and there is no anemia or thrombocytopenia in the routine blood test except for 13 units of leukocytes, the patient’s 13 units of leukocytes is most likely caused by a respiratory tract infection, and usually After anti-infection treatment, the patient may be cured without serious consequences. However, if the patient has 13 units of leukocytes in routine blood tests, along with anemia and thrombocytopenia, acute leukemia cannot be ruled out and a bone marrow aspiration is often required to confirm the diagnosis. If the diagnosis of acute leukemia is confirmed, the consequences are very serious. Therefore, whether 13 units of leukocytes is serious or not, it is important to look not only at the number of leukocytes itself, but also at the patient’s symptoms and, crucially, to understand the specific cause of the elevated leukocytes.