The entire process produces an inflammatory response in the infected area, which appears on the body's surface as redness, swelling, and heat. Because neutrophils generally make up over 70 percent of the white blood cells, a decrease in the number of white blood cells usually means a decrease in the total number of neutrophils. Without the key neutrophil defense, a person could die of an infection. Causes Neutropenia has a number of causes. The number of neutrophils can decrease because bone marrow production isn't adequate or because large numbers of white blood cells are destroyed in the circulation.
Aplastic anemia causes neutropenia as well as deficiencies in other types of blood cells.
Certain rare hereditary diseases, such as infantile genetic agranulocytosis and familial neutropenia, also cause decreases in the number of white blood cells. People who have cyclic neutropenia are prone to infections when the number of neutrophils is low. Some people who have cancer, tuberculosis, myelofibrosis, vitamin B 12 deficiency, or folic acid deficiency develop neutropenia. Neutrophils are destroyed faster than they're produced in some bacterial infections, some allergic disorders, some autoimmune diseases, and some drug treatments. Because neutropenia has no specific symptoms, it's likely to go unnoticed until an infection occurs.