Neutrophil percentage that is slightly lower than normal and the number of leukocytes and granulocytes is not abnormal may be the result of certain pathogenic infections that have not returned to normal, etc. and is not clinically instructive. However, it may also be caused by the occurrence of other diseases or damage from physical or chemical factors. Common causes of low neutrophil percentage include the following: 1. Infections: Commonly seen in Gram-negative bacterial infections, such as typhoid or S. paratyphi infections when both leukocyte and neutrophil counts are abnormally reduced. Certain viral infectious diseases such as influenza, chickenpox, and fever with thrombocytopenia syndrome caused by new bunyavirus infections can also cause a decrease in leukocytes and thus a decrease in the percentage of neutrophils. Some protozoal infections, such as malaria, can also cause low neutrophil percentage; 2, hematologic diseases: some hematologic diseases such as aplastic anemia, paroxysmal sleep hemoglobinuria, lymphoma, hemophagocytic syndrome, etc., can lead to a decrease in neutrophil percentage and can often be accompanied by a decrease in platelets and red blood cells; 3, monocyte macrophage system hyperfunction: different causes of 3, hyperfunction of the mononuclear macrophage system: splenomegaly and hypersplenism caused by different reasons may also lead to low neutrophil percentage, such as various causes of cirrhosis or portal hypertension. and chemical drugs, antineoplastic drugs and antidiabetic drugs, etc., produce myelosuppression and affect hematopoietic stem cells, which can also lead to a decrease in neutrophil percentage.