Fever Introduction and Definition

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Fever Introduction and Definition

Fever is elevation of body temperature, which is defined as rectal temperature 100.40F (38.C) or more. In a normall person, the body temperature fluctuates within 99.7-100.20F (36.6-37.90C) with highest temperature in the early evening and lowest in the morning.

(Fever more than 104.F (40.C) is known as hyperpyrexla. This high temperature can develop in patients with severe infection and also due to central nervous system (CNS) pathology like hemorrhage. )

Types ofFever

There are three classical types of fever but with the early use of antipyretics and antibiotics these days they are rarely encountered.

Continuous Fever

fever does not fluctuate more than 1.50F (10C) during 24 hours period and never touches the baseline or normal level.

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Remittent Fever

Fever fluctuates more than 2.C without touching the normal lever

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Intermittent Fever

Fever is present only for few hours during 24 hours period. If paroxysms of fever occur everyday, it is called quotidian; if it occurs in alternate day, tertian and if it occurs after 2 days, quartan

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Biphasic fever is a single illness where two periods of fever occurs which has a normal phase in between (saddle backi fever).


CMost fevers are associated with single viral infections which are sel-imiting and need no treatment. Fever is a reaction to limit microbial growth and as such is not going to harm the individual. However, fever with temperature above 39.can be extremely uncomfortable for the child which may need treatment. Similarly, in children suffering from some other underlying diseases like heart failure or severe anemia, fever may cause further metabolic derangement which merits prompt treatment. In bacterial infection, antipyretics may maski the fever, thereby causing doubt whether antibiotic treatment is useful or not. Similarly, in certain infection, the fever pulse relationship gives a clue to the diagnosis which may be masked by antipyretics.

Antipyretics are used only for symptomatic relief and do not alter the course of the disease. If parents find fever Causing excessive discomfort to the child, then antipyretics may be justified. Antipyretics may also be given to children with cardiopulmonary, metabolic, or other diseases in which fever adds to the metabolic demand.

Key Message

U Fever occurs when the hypothalamic set point is raised D Fever should be distinguished from hyperthermia, the later may be rapidly fatall

L Fever more than 104 F (40.C) is known as hyperpyrexia UThere are four final diaqnosis of fever of unknown origininfections, noninfectious inflammatory disease, neoplasm and miscellaneous causes

U Fever may remain undiagnosed in a number of cases, where even after extensive investigation the etiology may not be found U Most fevers are associated with a single self-limiting viral infection, where no treatment is needed