leukopenia

Leukopenia is a reduction in circulating white blood cells (WBCs). In adults, a total WBC count below about 4,000 cells per microliter is commonly described as leukopenia, though neutropenia (low neutrophils) is the most clinically relevant form because neutrophils defend against bacterial infections.

Causes include decreased production (bone marrow failure, aplastic anemia, myelodysplastic syndromes, vitamin B12 or folate deficiency, chemotherapy or radiation), increased destruction or sequestration (autoimmune neutropenia, hypersplenism), and redistribution during infection. Medications such as cytotoxic chemotherapy, immunosuppressants, and some antipsychotics (for example clozapine) are common drug-induced causes.

Many patients are asymptomatic. When present, symptoms reflect infections, such as fever or localized infections. Diagnosis is by complete blood count with differential and calculation of the absolute neutrophil count (ANC). Severe neutropenia is usually ANC < 500/µL; mild to moderate neutropenia ranges higher. Additional tests may evaluate marrow function and nutritional status.

Management targets the underlying cause and infection prevention. Interventions may include stopping causative drugs, treating nutritional deficiencies, or treating marrow disorders. In chemotherapy-related neutropenia, granulocyte colony-stimulating factors (G-CSF) can shorten duration. Preventive measures include vaccination, hand hygiene, and prompt treatment of infections.

Prognosis varies with cause and patient health. Leukopenia due to reversible factors often improves with treatment; chronic marrow disease carries higher infection risk and poorer outlook. It is commonly evaluated before procedures or during cancer treatment to balance infection risk with other therapies.