Neutrophils are a type of white blood cell, and a low percentage of neutrophils occurs when the number of neutrophils in the blood is reduced. A low percentage of neutrophils may be physiological and is usually of no particular clinical significance and may be observed first. In addition to physiological factors, low neutrophil percentage may also result from the presence of infections, physicochemical factors, hematologic disorders, and autoimmune system disorders. The following are common cases of low neutrophil percentage: 1. Infections: A variety of pathogenic microbial infections can result in low neutrophil percentage. Bacterial infections are common in patients with typhoid fever and cornual tuberculosis, and viral infections are seen in patients with influenza, measles, rubella, and novel Bunyavirus infection causing fever with thrombocytopenia syndrome. Other pathogenic microorganisms, such as human granulocyte anaerobic infection, mainly destroy neutrophils and can lead to a significant decrease in the percentage of neutrophils. In addition, leishmanial protozoan infections cause a prominent manifestation of black fever with a low neutrophil percentage. These cases are treated mainly with anti-infection, and will recover after the infection is controlled; 2. Physical and chemical factors: patients with radiotherapy, chemotherapy and long-term exposure to X-rays can have low neutrophil percentages. Long-term exposure to radiation should be avoided. For patients with severe neutrophil hypoglobulinemia, suspension of radiation and chemotherapy should be considered according to the situation to lift the bone marrow suppression. Drugs that elevate white blood cells can also be applied to promote normalization of neutrophils. In addition, some antipyretics, antibacterial drugs, interferons, and drugs for hyperthyroidism such as methimazole and propylthiouracil can also have low neutrophil percentage, which should be discontinued and replaced by other treatments or changed to other drugs; 3. percentage is low. It is necessary to actively treat the primary disease, improve bone marrow hematopoietic function and correct anemia. For example, lymphoma can be treated with radiotherapy, chemotherapy and surgery, and if necessary, hematopoietic stem cell transplantation. Generally, glucocorticoids can be applied to treat SLE, and those with serious conditions are considered to be treated with immunosuppressants, which can alleviate the destruction of neutrophils by antibodies by controlling the disease, while paying attention to diet and rest to improve body resistance; 5. Other: patients with cirrhosis and non-cirrhotic portal hypertension with splenomegaly and hypersplenism can destroy white blood cells and platelets, and the main destruction of white blood cells is Neutrophils predominate, which leads to low percentage of neutrophils. Severe impairment of liver function should be treated with reasonable medication under the guidance of a physician. Severe decrease in neutrophil percentage can be treated with drugs such as recombinant human granulocyte colony-stimulating factor, and if necessary, partial splenic artery embolization should be considered. Low neutrophil percentage requires active search for the cause and the principle of treatment is based on removing the cause.