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For further information, see CMDT Part 13-22: Neutropenia

Key Features

Essentials of Diagnosis

  • Neutrophils < 1800/mcL (1.8 × 109/L)

  • Severe neutropenia if neutrophils < 500/mcL (0.5 × 109/L)

General Considerations

  • Patients with neutropenia are vulnerable to gram-positive and gram-negative bacterial and fungal infections

  • Risk of infection is related to the severity of neutropenia

  • Patients with "chronic benign neutropenia" are free of infection despite very low stable neutrophil counts

  • In patients with cyclic neutropenia, the neutrophil count oscillates (usually in 21-day cycles) between normal and low, with infections occurring during the nadirs

  • Congenital neutropenia is lifelong neutropenia punctuated with infection

  • Both cyclic neutropenia and congenital neutropenia represent problems in mutations in the neutrophil elastase gene ELANE (also called ELA-2)


  • A variety of bone marrow disorders and nonmarrow conditions may cause neutropenia (Table 13–12)

  • All the causes of aplastic anemia and pancytopenia may cause neutropenia

    • Causes of aplastic anemia

      • Autoimmune: idiopathic, systemic lupus erythematosus

      • Congenital: defects in telomere length maintenance or DNA repair (rare)

      • Chemotherapy, radiotherapy

      • Toxins: benzene, toluene, insecticides

      • Medications: chloramphenicol, gold salts, sulfonamides, phenytoin, carbamazepine, quinacrine, tolbutamide

      • Post-viral hepatitis (A, B, C, E, G, non-A through -G)

      • Non-hepatitis viruses (Epstein-Barr virus, parvovirus, cytomegalovirus, echovirus 3, others)

      • Pregnancy

      • Paroxysmal nocturnal hemoglobinuria

    • Causes of pancytopenia

      • Aplastic anemia

      • Myelodysplasia

      • Acute leukemia

      • Chronic idiopathic myelofibrosis

      • Infiltrative disease: lymphoma, myeloma, carcinoma, hairy cell leukemia, etc

      • Hypersplenism (with or without portal hypertension)

      • Systemic lupus erythematosus

      • Infection: tuberculosis, HIV, leishmaniasis, brucellosis, cytomegalovirus, parvovirus B19

      • Nutritional deficiency (megaloblastic anemia)

      • Medications

      • Cytotoxic chemotherapy

      • Ionizing radiation

  • New onset of an isolated neutropenia is most often due to an idiosyncratic reaction to a drug

  • Agranulocytosis (complete absence of neutrophils in the peripheral blood) is almost always due to a drug reaction

  • Neutropenia in the presence of a normal bone marrow may be due to

    • Immunologic peripheral destruction (autoimmune neutropenia)

    • Sepsis

    • Hypersplenism

  • Isolated neutropenia is an uncommon presentation of hairy cell leukemia or a myelodysplastic syndrome

  • Myelosuppressive cytotoxic chemotherapy causes neutropenia in a predictable manner

Table 13–12.Causes of neutropenia.

Clinical Findings

  • Neutropenia results in

    • Stomatitis

    • Infections due to gram-positive or gram-negative aerobic bacteria or to fungi such as Candida or Aspergillus

  • Most common infectious syndromes

    • Septicemia

    • Cellulitis

    • Pneumonia

    • Neutropenic fever of unknown origin

  • Fever should always be assumed to be of infectious origin until proven ...

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