Neutropenia, is defined as neutrophils <2.0×10^9/L in adults; neutrophils <1.8×10^9/L in children ≥10 years of age; neutrophils <1.5×10^9/L in children <10 years of age. 1. Neutrophils are generated in the bone marrow, which can be divided into proliferative and storage pools. Adults produce 1×10^9/L neutrophils per day from the bone marrow, of which about 90% are stored in the bone marrow and about 10% are released into the peripheral blood, while about half of the latter are in the circulating pools and the other half are in the limbic pools, and the two can be exchanged freely to achieve a dynamic equilibrium. 2. Common causes of neutropenia include decreased production, as in leukemia, which affects the normal proliferation of bone marrow; excessive destruction, as in severe infections, which result in increased consumption of neutrophils in the bloodstream or at the site of inflammation; and distributional abnormalities, as in pseudo-granulocytopenia, in which the shift of neutrophils to the limbic pool leads to a relative decrease in the circulating pool of granulocytes, but not a decrease in the total number of granulocytes. If you suffer from neutropenia, it is recommended that you visit a regular hospital to avoid delays.