Febrile Neutropenia

Febrile neutropenia is a time-critical infection syndrome in a person whose neutrophil-mediated defence is severely impaired. It is defined as a single oral temperature ≥38.3 °C, or a temperature ≥38.0 °C lasting at least 1 hour, together with an absolute neutrophil count (ANC) <0.5 × 10⁹/L or an ANC expected to fall below that threshold within 48 hours. The ANC matters more than the total white blood cell count because it estimates the circulating neutrophils available to contain bacterial and fungal invasion. When neutrophils are depleted, small breaks in the oral, respiratory, gastrointestinal, urinary, or skin barriers can become portals for bloodstream infection. Mucositis makes this risk higher by damaging the normal mucosal barrier. Fever is often the earliest or only visible sign. Neutropenic patients may not produce the erythema, swelling, purulent drainage, or focal tenderness that would normally help localize infection. A patient can therefore look surprisingly well while infection is already progressing. The danger is not reduced by a quiet examination; it is increased by the absence of the usual inflammatory clues. The syndrome commonly follows myelosuppressive cancer...