Fever

Abstract 

Fever results from a rise in the hypothalamic set point due to an elevation of prostaglandin E2 in the brain as a result of an increased synthesis of this substance caused by exogenous pyrogens and pyrogenic cytokines. Patients with acute fever should be promptly assessed for signs of sepsis. Pyrexia of unknown origin (PUO) is defined as a fever higher than 38.3 °C on several occasions during at least 3 weeks, with uncertain diagnosis after a number of obligatory tests. No diagnosis is reached in up to 50% of cases. A diagnostic algorithm is proposed in which the most important steps are history-taking, physical examination and the obligatory investigations in a search for potentially diagnostic clues (PDCs). Scintigraphic methods, such as 67gallium citrate, labelled leukocytes and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), are often used in PUO. Because of favourable characteristics of FDG-PET, conventional scintigraphic techniques may be replaced by FDG-PET in institutions where PET is available. Most patients with undiagnosed PUO have benign self-limiting or recurrent fever.

Keywords: diagnostic algorithm, fever, periodic fever, pyrexia of unknown origin