The normal value of neutrophil percentage in adults is 50%-70%, and in infants and children under 3 years of age the percentage of neutrophils is 20%-40%. The most common cause of increased neutrophil percentage is due to various acute infections, especially acute septic bacterial infections, and increased neutrophil percentage can also occur with severe tissue injuries, after larger surgeries, and large burns. In addition, an increase in neutrophil percentage can also occur when the body is acutely intoxicated or under stressful conditions, such as after emotional stress or heavy exercise. A decrease in neutrophil percentage is common in patients with malignant tumors after chemotherapy, where the hematopoietic function of the bone marrow is suppressed and a decrease in neutrophil percentage may occur. Various viral infections, such as influenza virus and rubella virus, can also reduce the neutrophil percentage.