Leukopenia

Leukopenia is a hematologic abnormality defined as a reduced total white blood cell (WBC) count—typically below 4,000–5,000 leukocytes/µL, depending on laboratory reference ranges. As white blood cells (leukocytes) are essential for immune defense, leukopenia predisposes individuals to increased susceptibility to infections and impaired wound healing.

Etiology and Classification

Leukopenia may arise from decreased production, increased destruction, or sequestration of leukocytes. It is often categorized by the predominant cell line affected—most commonly neutropenia (low neutrophils), but it may also involve lymphocytes, monocytes, eosinophils, or basophils.

Common Causes

Category

Examples

Infections

Viral (influenza, HIV, hepatitis, EBV, COVID-19), severe bacterial sepsis, tuberculosis, malaria, dengue wikipedia+2

Bone marrow disorders

Aplastic anemia, leukemia, lymphoma, myelodysplastic syndrome, myelofibrosis, multiple myeloma clevelandclinic+2

Cancer therapies

Chemotherapy, radiation therapy, bone marrow/stem cell transplantation

Autoimmune diseases

Systemic lupus erythematosus, rheumatoid arthritis, Sjögren’s syndrome, granulomatosis with polyangiitis britannica+2

Medications

Immunosuppressants, antithyroid drugs, anticonvulsants, certain antibiotics (e.g., sulfonamides, penicillins) britannica+2

Nutritional deficiencies

Vitamin B12, folate, copper, or zinc deficiency wikipedia+2

Other

Hypersplenism, congenital neutropenias (e.g., Kostmann syndrome), sarcoidosis, severe malnutrition templehealth+1

Clinical Features and Diagnosis

Patients are often asymptomatic until an infection occurs. Signs may include recurrent fevers, oral ulcers, skin infections, or delayed recovery from illness. Diagnosis relies on a complete blood count (CBC) with differential. Further evaluation—such as peripheral smear, bone marrow biopsy, vitamin levels, or serologic testing—is guided by clinical suspicion.

Management

Treatment targets the underlying cause: discontinuing offending drugs, correcting nutritional deficits, treating infections, or managing bone marrow disorders. In severe neutropenia, growth factors (e.g., G-CSF) or prophylactic antibiotics may be indicated.