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Published on: June 15, 2019
[Infections and fever]
1I. Medizinische Klinik und Poliklinik, Universitätsklinikum Hamburg-Eppendorf (UKE), Martinistr. 52, 20246, Hamburg, Deutschland. s.schmiedel@uke.de.
Abstract:
Fever can be due to infectious or noninfectious causes and results from the body's natural response to exogenous or endogenous pyrogens. Laboratory tests including complete blood count, differential blood count, C‑reactive protein, erythrocyte sedimentation rate and procalcitonin do not have sufficient sensitivity and specificity to definitively detect or rule out an infectious (bacterial, viral, parasitic) cause of fever. Blood cultures should be carried out when bacteremic or septic illnesses are suspected. Fever is not always present in infections and can be absent, especially in older and immunocompromised patients. If fever is suspected, core temperatures should be taken, e.g., rectally, orally or invasively. Depending on the clinical situation, infectious causes must be excluded as the most likely cause of an acutely occurring fever. The investigation of long-standing fever (fever of unknown origin, FUO) can be complex and some infectious diseases should first be ruled out, whereby a syndromic classification often helps to clarify the cause of the fever.
Insights
Fever has many causes, and common lab tests are not always reliable for diagnosing infections. Investigating fever, especially prolonged cases, requires careful exclusion of infectious diseases.
Area of Science:
- Internal Medicine
- Infectious Diseases
- Clinical Diagnostics
Background:
- Fever is a common symptom with diverse origins, including infections and non-infectious conditions.
- It represents the body's physiological response to pyrogens.
- Standard laboratory tests often lack the definitive accuracy to pinpoint infectious fever causes.
Purpose of the Study:
- To review the diagnostic challenges and strategies for identifying the causes of fever.
- To emphasize the importance of accurate temperature measurement and clinical evaluation.
- To highlight the complexity of investigating fever of unknown origin (FUO).
Main Methods:
- Literature review of diagnostic approaches for fever.
- Discussion of the limitations of common laboratory markers (CBC, CRP, ESR, procalcitonin).
- Emphasis on the role of blood cultures in suspected bacteremia or sepsis.
Main Results:
- Laboratory tests lack sufficient sensitivity and specificity for definitive infectious etiology.
- Fever may be absent in certain patient groups, such as the elderly or immunocompromised.
- Accurate core temperature measurement is crucial for fever confirmation.
Conclusions:
- Excluding infectious causes is paramount in acute fever evaluation.
- Syndromic classification aids in diagnosing complex cases of fever of unknown origin.
- A systematic approach is necessary for effective fever workup.
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