July 03, 2010

Abnormal body temperatures and febrile convulsion

Also called pyrexia, fever is abnormal rise in body temperature of a person above the normal of 37.2° C.
Body temperature normally vary between 36.4 - 37.2° C (i.e. 97.5 - 98.9° F), with the lower levels in the mornings (6 AM) and the higher levels in the evenings (4-6 PM).

Control of body temperature is regulated by the thermo-regulatory center in the brain; which sets a normal temperature point for the body. Fever results when pyrogens cause an increase of this set point such that the body sees the new set point as its 'normal' temperature.

Fever is a common symptom usually signifying infections like malaria, tuberculosis, meningitis; malignancies like leukemia, lymphoma; and many other conditions.

It can be damaging especially to children below the age of six years, in whom it may easily cause a convulsion - febrile convulsion (see what to do below).

Hyperpyrexia, hyperthermia and hypothermia

Hyperpyrexia is fever of more than 41.5° C (>106° F). It can develop in people with severe infections, but also in those with central nervous system (CNS) hemorrage, local trauma or tumor.

Hyperthermia occurs if there is an unchanged normal set point of the thermo-regulatory center in the brain, but an uncontrolled rise in body temperature that exceeds the body’s ability to lose this extra heat. Causes include working or exercising in abnormally hot environments; taking recreational drugs like cocaine; inhalational anaesthesia, thyrotoxicosis; some types of stroke; pheochromacytoma; status epilepticus; and many others.

Hypothermia is unintentional drop in the body temperature to below 35° C (95° F). It may occur in a previously healthy person who is exposed to severe cold like in the elderly, the very young, and as an occupational hazard e.g. the military; or when it complicates serious systemic disease e.g. hypothyroidism; hypoglycemia; hypopituitarism; sepsis.

The appearance of a rash with fever should prompt an immediate visit to the doctor. It could be a sign of serious disease as in measles, HIV, typhoid fever, systemic lupus erythomatosus, syphilis, drug reaction and many others.


Especially for children between 6 months - 6 years; rapidly bring down the temperature thus: tepid-sponge (i.e. apply lukewarm water to the exposed body), give an antipyretic, and seek proper medical evaluation. Children of this age bracket are very prone to febrile convulsions, thus the need for urgent resolution of fever in them.

Hypothermic individuals must be rewarmed by covering and insulating them in a warm environment. Hot water bottles may be used. Seek expert medical help urgently.

For hyperthermia, physical cooling with sponging, fans, cooling blankets, and even ice baths should be initiated. An urgent visit to the doctor for more specific and technical measures is indicated.

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