Leukopenia

An abnormally low number of circulating white blood cells below the lower limit of the normal reference range (adults: <4 × 10⁹/L), typically reflecting reduced leukocyte production, increased destruction, or splenic sequestration, and associated with increased susceptibility to infection.

Causes

• Bone marrow disorders

  • Leukemia

  • Aplastic anemia

  • Myelofibrosis

  • Myelodysplastic syndrome

  • Bone marrow infiltration by malignancy

• Cancer therapy

  • Chemotherapy

  • Radiation therapy

• Infections causing bone marrow suppression

  • Epstein–Barr virus (EBV)

  • Human immunodeficiency virus (HIV/AIDS)

  • Viral hepatitis

  • Sepsis

• Autoimmune causes

  • Systemic lupus erythematosus (SLE)

  • Rheumatoid arthritis

  • Autoimmune neutropenia

• Nutritional causes

  • Vitamin B12 deficiency

  • Folate deficiency

  • Copper deficiency

  • Malnutrition

• Medication-related causes

  • Antibiotics

  • Antipsychotics

  • Immunosuppressive medications

  • Antithyroid drugs

  • Anticonvulsants

• Splenic causes

  • Hypersplenism

  • Splenomegaly with increased leukocyte sequestration

• Other causes

  • Congenital leukocyte disorders

  • Alcohol abuse

  • Idiopathic leukopenia