Hematologic Conditions: Leukopenia.

Leukopenia is a common finding in the outpatient setting. It typically occurs because of a significant reduction in neutrophils, which comprise 50% to 70% of circulating leukocytes. Neutropenia is defined as an absolute neutrophil count (ANC) of less than 1,500/mcL. Neutropenia is classified by whether it is transient or chronic. Chronic neutropenia can be further described as extrinsic or intrinsic. Extrinsic causes are varied. Intrinsic causes can include impaired proliferation and maturation of myeloid progenitor cells in the bone marrow. Assessment of patients with neutropenia should be guided by the severity on presentation. The duration of leukopenia and the clinical status of the patient also should be considered. Some patients with neutropenia can develop life-threatening bacterial infections. In neutropenic patients, the risk of febrile neutropenia should be assessed systematically. Patients with febrile neutropenia should undergo treatment with antibiotics. Other treatments are aimed at management of the underlying cause of neutropenia.