Neutropenia is a decrease in circulating neutrophils in the nonmarginal pool, which constitutes 4%-5% of total body neutrophil stores. Most of the neutrophils are contained in the bone marrow, either as mitotically active (one third) or postmitotic mature cells (two thirds). Neutropenia is classified as mild, moderate, or severe based on the absolute neutrophil count (ANC). Mild neutropenia is present when the ANC is 1000-1500 cells/µL, moderate neutropenia is present with an ANC of 500-1000/µL, and severe neutropenia refers to an ANC lower than 500 cells/µL. The risk for bacterial infection is related to both the severity and duration of the neutropenia.
The risk for serious infection increases as the ANC falls to the severely neutropenic range (<500/µL). The term agranulocytosis is used to describe a more severe subset of neutropenia. Agranulocytosis refers to a virtual absence of neutrophils in peripheral blood. It is usually applied to cases in which the ANC is lower than 100/μL. The duration and severity of neutropenia directly correlate with the total incidence of all infections and of those infections that are life-threatening.
Test your knowledge on the presentation, workup, and treatment for neutropenia and related conditions with this short quiz.
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Cite this: Elwyn C. Cabebe. Fast Five Quiz: How Much Do You Know About Neutropenia? - Medscape - Nov 22, 2017.