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Fever of Unknown Origin 

Fever of Unknown Origin
Fever of Unknown Origin

Mary J. Kasten

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date: 09 July 2020

Classic definition of fever of unknown origin (FUO) is a fever for more than 3 weeks, a temperature of 38.3 C or higher on several occasions, and no definitive diagnosis after 1 week of hospital evaluation. Recent series have used other criteria instead of 1 week of hospital evaluation: 1 week of intensive outpatient evaluation, 3 outpatient visits, or a battery of laboratory tests. A comprehensive history should be obtained and a physical examination and basic laboratory and radiographic testing should be performed before stating that a patient has FUO. There is no clear consensus in the literature for defining the minimal diagnostic evaluation. The common causes of FUO are infection, cancer, rheumatologic or autoimmune disorders, and miscellaneous hematologic conditions. Treatment is empirical if a cause is not found.

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