The common causes of low neutrophil ratio are infections, hematologic diseases, injuries from physical and chemical factors, hyperactive monocyte macrophage system and autoimmune diseases.
1. Infections: Gram-negative bacilli, such as typhoid fever; viral infections, such as influenza; and infections of certain pathogens, such as malaria, can lead to a decrease in the ratio of white blood cells to neutrophils.
2. Hematological diseases: such as aplastic anemia, megaloblastic anemia, metastatic carcinoma of bone marrow and other diseases can lead to the decrease of white blood cells, and at the same time, the decrease of platelets and red blood cells can also occur.
3. Damage of physical and chemical factors: X-ray, radionuclide and other physical factors, as well as benzene, lead, antitumor drugs, antidiabetic drugs can also cause leukopenia and neutrophil reduction.
4. Hyperfunction of mononuclear phagocyte system: splenomegaly and hyperfunction caused by various diseases, such as portal cirrhosis, can also lead to leukopenia and neutrophilia.
5. Autoimmune diseases: a common disease is systemic lupus erythematosus, which can also lead to leukopenia.
The absolute value of neutrophil is less than 1.5×10^9/L, which is called granulocytopenia, and the cause of the disease should be identified.