granulocytopenia

Granulocytopenia refers to a reduced number of granulocytes, a class of white blood cells that includes neutrophils, eosinophils, and basophils. The clinical concern is mainly neutropenia, since neutrophils are the primary defenders against bacteria and fungi. The absolute neutrophil count (ANC) is used to gauge severity; an ANC below 1.5 × 10^9/L is low, with severe neutropenia often defined as ANC below 0.5 × 10^9/L (500/µL).

Causes are diverse and include decreased production in the bone marrow (cytopenias from chemotherapy, aplastic anemia, myelodysplastic syndromes, leukemia, nutritional deficiencies), increased destruction (autoimmune neutropenia), sequestration (hypersplenism), drug effects (chemotherapy, clozapine, antithyroid drugs, certain antibiotics), infections, and congenital neutropenias. Transient neutropenia can accompany viral illnesses.

Clinically, patients may be asymptomatic or present with fever and infections. In neutropenia, typical inflammatory signs may be blunted. Evaluation relies on a complete blood count with differential and calculation of the ANC; persistent or unexplained granulocytopenia may require bone marrow examination, imaging, and additional tests to determine underlying causes.

Management aims to treat the cause, prevent infection, and support recovery. Offending drugs are stopped when feasible; infection control and patient education are important. In selected cases, granulocyte colony-stimulating factor (G-CSF) accelerates neutrophil recovery. Febrile neutropenia is treated as a medical emergency with empiric broad-spectrum antibiotics, and hospitalization is often required for severe cases. Prognosis varies with etiology and overall health.