How is neutropenia classified?

Updated: May 20, 2021
  • Author: Carly DeFaria, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Neutropenia is classified as mild, moderate, or severe, based on the ANC, as follows:

  • Mild neutropenia: ANC 1000-1500 cells/µL
  • Moderate neutropenia: ANC 500-1000/µL
  • Severe neutropenia: ANC < 500 cells/µL

The risk of bacterial infection rises not only with the severity of neutropenia but also its duration.

The term agranulocytosis is used to describe a more severe subset of neutropenia. Agranulocytosis refers to a virtual absence of neutrophils in peripheral blood. In these cases the ANC is typically lower than 100/μL. [14, 15, 16, 17] The reduced number of neutrophils makes patients extremely vulnerable to infection. [14, 18] Cardinal signs include fever, sepsis, and other manifestations of infection. Causes can include drugs, chemicals, infective agents, ionizing radiation, immune mechanisms, primary bone marrow failure syndromes, and heritable genetic aberrations.

Some cases, including benign familial neutropenia (see Pediatric Autoimmune Neutropenia), are characterized by only mild neutropenia and are of no obvious significance for health. [14] This article is limited to discussing neutropenia (ANC < 1500/µL) and agranulocytosis (ANC < 100/µL). It does not address the transient neutropenia associated with cancer chemotherapy (for that, see Antimicrobial Agents in Neutropenic Cancer Patients), nor does it consider agranulocytosis occurring as part of primary marrow-failure syndromes (eg, aplastic anemia, pancytopenia, acute leukemia, myelodysplastic syndromes).

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