Definition

• Neutrophil count < 1500

• Fever in immunocompromised

Bone marrow disorders

• Aplastic anemia
• Drugs: sulfonamides, chlorpromazine, procainamide, penicillin, cephalosporins, cimetidine, methimazole, phenytoin, chlorpropamide, antiretrovirals
• Cyclic neutropenia
• Pure white cell aplasia
• "Chronic benign neutropenia" in African-American and other populations
• Congenital (rare)

Peripheral disorders

• Hypersplenism
• Sepsis
• Immune destruction, eg, systemic lupus erythematosus (SLE)
• Felty’s syndrome (with rheumatoid arthritis and splenomegaly)
• HIV infection
• Acute viral infection
• Large granular lymphocytosis