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Contents
  • Understanding FUO
  • Common Causes of FUO
  • Geographic and Demographic Influences

What Causes Fever of Unknown Origin in Adults?

What Causes Fever of Unknown Origin in Adults?

The Big Picture

Fever of unknown origin (FUO) in adults can be puzzling and challenging to diagnose. Discover the common causes of this mysterious condition.
Contents
  • Understanding FUO
  • Common Causes of FUO
  • Geographic and Demographic Influences

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%.
Fever of unknown origin (FUO) is a prolonged fever of over 38.3˚C (100.9˚F) lasting more than three weeks without an identified cause despite extensive investigations.

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.

FAQs

What is FUO?

FUO is a prolonged fever with no identified cause after thorough evaluation.

What are common causes of FUO?

Infections, rheumatologic conditions, and malignancies are common causes.

How does geography affect FUO?

Geographic location influences prevalent infections causing FUO.

Can FUO be undiagnosed?

Yes, some cases remain undiagnosed despite extensive evaluation.

Key Takeaways

Understanding the diverse causes of FUO is crucial for effective diagnosis and management.
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Additional References
  1. Cunha BA, Lortholary O, Cunha CB. Fever of unknown origin: a clinical approach. Am J Med 2015; 128:1138.e1.
  2. 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.
  3. 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.
  4. 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.