Agranulocytosis is defined as which of the following?

• A. Lowering of white blood cell count
• B. Increase in white blood cell count
• C. Decreased platelets
• D. Decreased red blood cells

Answer: (A)

Agranulocytosis is a severe neutropenia, meaning a dramatic drop in neutrophils, the white blood cells most important for fighting bacterial infections. When neutrophil counts fall to critically low levels—often described as an absolute neutrophil count below about 500 cells per microliter—the risk of serious infections skyrockets, which is the defining danger of this condition. The description that fits this concept best is a lowering of white blood cell count, since neutrophils are a key subset of those cells. The other options point to an increase in white blood cells or to reductions in other blood components (platelets or red blood cells), which do not describe agranulocytosis. Clinically, patients may present with fever, sore throat, or other signs of infection, and neutropenic fever is a medical emergency requiring prompt evaluation, withdrawal of any offending drug, infection workup, and treatment with antibiotics as indicated; growth factors to stimulate neutrophil production may be used in some cases.