Fever
Fever | |
An analogue medical thermometer showing the temperature of 38.7 °C |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]; M.Umer Tariq [3]
Synonyms and keywords: Pyrexia; febrile response
Types
Pyrexia (fever) can be classed as:
- Low grade: 38–39°C (100.4–102.2°F)
- Moderate: 39–40°C (102.2–104.0°F)
- High-grade: 40–42°C (104.0–107.6°F)
- Hyperpyrexia: over 42°C (107.6°F)
The last is clearly a medical emergency because it approaches the upper limit compatible with human life.
Most of the time, fever types can not be used to find the underlying cause. However, there are specific fever patterns that may occasionally hint the diagnosis:
- Pel-Ebstein fever: A specific kind of fever associated with Hodgkin's lymphoma, being high for one week and low for the next week and so on. However, there is some debate as to whether this pattern truly exists.[1]
- Continuous fever: Temperature remains above normal throughout the day and does not fluctuate more than 1°C in 24 hours, e.g. lobar pneumonia, typhoid, urinary tract infection, brucellosis, or typhus. Typhoid fever may show a specific fever pattern, with a slow stepwise increase and a high plateau.
- Intermittent fever: Temperature is present only for some hours of the day and becomes normal for remaining hours, e.g. malaria, kala-azar, pyaemia, or septicemia. In malaria, there may be a fever with a periodicity of 24 hours (quotidian), 48 hours (tertian fever), or 72 hours (quartan fever, indicating Plasmodium vivax). These patterns may be less clear in travelers.
- Remittent fever: Temperature remains above normal throughout the day and fluctuates more than 1°C in 24 hours, e.g. infective endocarditis.
Febricula[2] is a mild fever of short duration, of indefinite origin, and without any distinctive pathology.
Common Causes
Fever is a common symptom of many medical conditions:
- Infectious disease, e.g. influenza, common cold, HIV, malaria, infectious mononucleosis, or gastroenteritis.
- Various skin inflammations, e.g. boils, pimples, acne, or abscess.
- Immunological diseases, e.g. lupus erythematosus, sarcoidosis, inflammatory bowel diseases.
- Tissue destruction, which can occur in hemolysis, surgery, infarction, crush syndrome, rhabdomyolysis, cerebral hemorrhage, etc.
- Drug fever
- Directly caused by the drug, e.g. lamictal, progesterone, or chemotherapeutics causing tumor necrosis.
- As an adverse reaction to drugs, e.g. antibiotics or sulfa drugs.
- After drug discontinuation, e.g. heroin withdrawal.
- Cancers, e.g. Hodgkin disease.
- Metabolic disorders, e.g. gout or porphyria.
- Thrombo-embolic processes, e.g. pulmonary embolism or deep venous thrombosis.
Persistent fever which cannot be explained after repeated routine clinical inquiries, is called fever of unknown origin.
Complete Differential Diagnosis of the Causes of Fever
In Alphabetical Order. [3] [4]
Complete Differential Diagnosis of the Causes of Fever
(By Organ System)
Usefulness of Fever
There are arguments for and against the usefulness of fever, and the issue is controversial.[5][6] There are studies using warm-blooded vertebrates[7] and humans[8] in vivo, with some suggesting that they recover more rapidly from infections or critical illness due to fever.
Theoretically, fever has been conserved during evolution because of its advantage for host defense.[5] There are certainly some important immunological reactions that are sped up by temperature, and some pathogens with strict temperature preferences could be hindered.[9] The overall conclusion seems to be that both aggressive treatment of fever[8] and too little fever control[5] can be detrimental. This depends on the clinical situation, so careful assessment is needed.
Fevers may be useful to some extent since they allow the body to reach high temperatures. This causes an unbearable environment for some pathogens. White blood cells also rapidly proliferate due to the suitable environment and can also help fight off the harmful pathogens and microbes that invaded the body.
Treatment
Fever should not necessarily be treated. Fever is an important signal that there's something wrong in the body, and it can be used for follow-up. Moreover, not all fevers are of infectious origin.
Even when treatment is not indicated, however, febrile patients are generally advised to keep themselves adequately hydrated, as the dehydration produced by a mild fever can be more dangerous than the fever itself. Water is generally used for this purpose, but there is always a small risk of hyponatremia if the patient drinks too much water. For this reason, some patients drink sports drinks or products designed specifically for this purpose.
Most people take medication against fever because the symptoms cause discomfort. Fever increases heart rate and metabolism, thus potentially putting an additional strain on elderly patients, patients with heart disease, etc. This may even cause delirium. Therefore, potential benefits must be weighed against risks in these patients. In any case, fever must be brought under control in instances when fever escalates to hyperpyrexia and tissue damage is imminent.
Treatment of fever should be based primarily on lowering the set-point, but facilitating heat loss may also contribute. The former is accomplished with antipyretics. Wet cloth or pads are also used for treatment, and applied to the forehead. Heat loss may be an effect of (possibly a combination of) heat conduction, convection, radiation, or evaporation (sweating, perspiration). This may be particularly important in babies, where drugs should be avoided. However, if water that is too cold is used, it induces vasoconstriction and prevents adequate heat loss.
References
Articles
- ↑ http://content.nejm.org/cgi/content/short/333/1/66
- ↑ Febricula, definition from Biology-Online.org, consulted June 7, 2006 http://www.biology-online.org/dictionary/Febricula
- ↑ Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:77 ISBN 1591032016
- ↑ Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:68 ISBN 140510368X
- ↑ 5.0 5.1 5.2 Schaffner A. Fever—useful or noxious symptom that should be treated? Ther Umsch 2006; 63: 185-8. PMID 16613288
- ↑ Soszynski D. The pathogenesis and the adaptive value of fever. Postepy Hig Med Dosw 2003; 57: 531-54. PMID 14737969
- ↑ Su, F.; Nguyen, N.D.; Wang, Z.; Cai, Y.; Rogiers, P.; Vincent, J.L. Fever control in septic shock: beneficial or harmful? Shock 2005; 23: 516-20. PMID 15897803
- ↑ 8.0 8.1 Schulman, C.I.; Namias, N.; Doherty, J., et al. The effect of antipyretic therapy upon outcomes in critically ill patients: a randomized, prospective study. Surg Infect (Larchmt) 2005; 6:369-75. PMID 16433601
- ↑ Fischler, M.P.; Reinhart, W.H. Fever: friend or enemy? Schweiz Med Wochenschr 1997; 127: 864-70. PMID 9289813
Books
- Rhoades, R. and Pflanzer, R. Human physiology, third edition, chapter 27 Regulation of body temperature, p. 820 Clinical focus: pathogenesis of fever. ISBN 0-03-005159-2
- Kasper, D.L.; Braunwald, E.; Fauci, A.S.; Hauser, S.L.; Longo, D.L.; Jameson, J.L. Harrison's Principles of Internal Medicine. New York: McGraw-Hill, 2005. ISBN 0-07-139140-1.
External Links
- What to do if your child has a fever from Seattle Children's Hospital
- Fever and Taking Your Child's Temperature
- US National Institute of Health factsheet
- BUPA factsheet
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