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What Causes Fever of Unknown Origin in Adults?
Published: Oct 11, 2023
Fever of unknown origin (FUO) in adults can be puzzling and challenging to diagnose. Discover the common causes of this mysterious condition.
Understanding FUO
FUO is defined as a prolonged fever of over 38.3˚C (100.9˚F) lasting more than three weeks without an identified cause, despite extensive investigations. This condition can be frustrating as over 200 potential causes have been documented. It is important to differentiate FUO from more typical fever cases, as the latter often resolve or develop clear symptoms.
Common Causes of FUO
The causes of FUO are broadly categorized into infections, rheumatologic conditions, malignancies, miscellaneous causes, and undiagnosed cases. Infections account for about 34-39% of cases, with tuberculosis being a leading cause. Rheumatologic conditions like adult-onset Still's disease contribute to around 20% of cases, while malignancies such as lymphoma represent 12-16%.
Geographic and Demographic Influences
The causes of FUO can vary significantly based on geographic location and patient demographics. Infections are more prevalent in certain regions, with specific diseases like brucellosis being common in the Mediterranean. Older adults are more likely to have an identifiable cause, while younger adults often remain undiagnosed.
Frequently Asked Questions
FUO is a prolonged fever with no identified cause after thorough evaluation.
Infections, rheumatologic conditions, and malignancies are common causes.
Geographic location influences prevalent infections causing FUO.
Yes, some cases remain undiagnosed despite extensive evaluation.
Key Takeaways
Understanding the diverse causes of FUO is crucial for effective diagnosis and management.
References
- Cunha BA, Lortholary O, Cunha CB. Fever of unknown origin: a clinical approach. Am J Med 2015; 128:1138.e1.
- Fusco FM, Pisapia R, Nardiello S, et al. Fever of unknown origin (FUO): which are the factors influencing the final diagnosis? A 2005-2015 systematic review. BMC Infect Dis 2019; 19:653.
- Wright WF, Mulders-Manders CM, Auwaerter PG, Bleeker-Rovers CP. Fever of Unknown Origin (FUO) - A Call for New Research Standards and Updated Clinical Management. Am J Med 2022; 135:173.
- Wright WF, Yenokyan G, Auwaerter PG. Geographic Influence Upon Noninfectious Diseases Accounting for Fever of Unknown Origin: A Systematic Review and Meta-Analysis. Open Forum Infect Dis 2022; 9:ofac396.
This article has been reviewed for accuracy by one of the licensed medical doctors working for Doctronic. Always discuss health information with your healthcare provider.
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