Pyrexia
| Fever | |
|---|---|
 |
|
| An analog medical thermometer showing a temperature of 38.8 °C or 101.8 °F | |
| Classification and external resources | |
| Specialty | Infectious disease, pediatrics |
| ICD-10 | R50 |
| ICD-9-CM | 780.6 |
| DiseasesDB | 18924 |
| MedlinePlus | 003090 |
| eMedicine | med/785 |
| MeSH | D005334 |
Fever, also known as pyrexia and febrile response, is defined as having a temperature above the normal range due to an increase in the body's temperature set-point. There is not a single agreed-upon upper limit for normal temperature with sources using values between 37.5 and 38.3 °C (99.5 and 100.9 °F). The increase in set-point triggers increased muscle contraction and causes a feeling of cold. This results in greater heat production and efforts to conserve heat. When the set-point temperature returns to normal, a person feels hot, becomes flushed, and may begin to sweat. Rarely a fever may trigger a febrile seizure. This is more common in young children. Fevers do not typically go higher than 41 to 42 °C (105.8 to 107.6 °F).
A fever can be caused by many medical conditions ranging from the not serious to potentially serious. This includes viral, bacterial and parasitic infections such as the common cold, urinary tract infections, meningitis, malaria and appendicitis among others. Non-infectious causes include vasculitis, deep vein thrombosis, side effects of medication, and cancer among others. It differs from hyperthermia, in that hyperthermia is an increase in body temperature over the temperature set-point, due to either too much heat production or not enough heat loss.
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Wikipedia