Neutropenia

An abnormally low absolute neutrophil count in peripheral blood (<1.5 × 10⁹ cells/L), resulting in impaired innate immune defense and increased susceptibility to bacterial and fungal infections.

Causes

• Medications causing bone marrow suppression or neutrophil destruction

  • Chemotherapy

  • Radiotherapy

  • Antibiotics

  • Anticonvulsants

  • Antihypertensive medications

  • Immunosuppressive drugs

• Bone marrow malignancy causing impaired granulopoiesis

  • Leukemia

  • Lymphoma

  • Myelodysplastic syndrome

  • Aplastic anemia

• Infections causing neutrophil depletion

  • Sepsis

  • Human immunodeficiency virus (HIV)

  • Epstein–Barr virus (EBV)

  • Influenza

  • Tuberculosis

  • Malaria

• Nutritional causes

  • Vitamin B12 deficiency

  • Folate deficiency

  • Copper deficiency

  • Severe malnutrition

• Autoimmune causes

  • Systemic lupus erythematosus (SLE)

  • Rheumatoid arthritis

  • Felty syndrome

  • Autoimmune neutrophil destruction

• Hypersplenism with increased neutrophil sequestration

• Genetic causes

  • Kostmann syndrome (severe congenital neutropenia)

  • Cyclic neutropenia