Severe neutropenia: a diagnostic approach

Severe neutropenia: a diagnostic approachNormal levels of neutrophils are essential to prevent infections.Neutropenia is a relatively common disorder most often due to chemotherapy treatments, adverse drug reactions, or autoimmune disorders.The differential diagnosis of neutropenia is broad and encompasses congenital, infectious, rheumatologic, and iatrogenic causes.1,2 Severe neutropenia or agranulocytosis, defined as an absolute neutrophil count of less than 0.5 × 10 9 /L (<500/µL), is uncommon but can cause morbidity and mortality from infections.Epidemiologic studies show a wide variation in the incidence of neutropenia among geographic regions, with an average annual incidence of 56.4 cases of neutropenia and 9.0 cases of agranulocytosis per million people in the United States. 1 Data from the International Agranulocytosis and Aplastic Anemia Study in Europe show an annual incidence of 6.2 cases of agranulocytosis per million people. 2 Both studies assessed only hospitalized patients with severe neutropenia due primarily to noncytotoxic drugs, infections, or immune disorders and excluded those patients who were treated with cytotoxic drugs.Male and nonwhite patients had an increased risk, and patients between 50 and 59 years of age had the highest risk.No epidemiologic studies adequately address the relative severity, frequency, and mortality of the different causes of neutropenia.In this review, we present the case of a patient with apparently acute severe neutropenia. Summary points• Patients with a neutrophil count of less than 0.5 ‫ן‬ 10 9 /L (500 cells/µL) and signs or symptoms of infection require immediate hospitalization and prophylactic antibiotic therapy• Severe neutropenia is most commonly due to cell destruction that is mediated by the immune system or hypoplasia, rather than sequestration• Drugs are the most common cause of neutropenia, and medicines that can cause neutropenia should be discontinued whenever possible• The appropriate use of cytokines is dependent on the underlying cause of neutropenia