Body temperature between 990 F – 1050 F and onwards is called pyrexia. Pyrexia is a symptom and not a disease. Normal body temperature changes during the day. In humans the traditional normal value for the oral temperature is 370 C [ 98.60 F ]. Various parts of the body have different temperature.

        Exercise, Stress and dehydration may cause a persons temperature to go up. In such cases, it is not considered a true fever. A fever may mean that there is something else going on in the body that is causing it.

TEMPERATURE – MEASUREMENT:

        Clinical thermometer is the commonest instrument used. It was discovered by Galileo galilei from Italy in the year 1593. For a precise measurement it should be kept under the tongue for 2-5 minutes.

PHYSIOPATHOLOGICAL CHANGES:

        The initiation of fever begins when exogenous and endogenous stimuli, including Pyrogens, are presented to specialized host cells, principally monocytes and macrophages.

        Endotoxin [ a hydrophobic lipopolysaccharide in cell walls of gram negative bacteria] Inflammation, Other Pyrogenic Stimuli.

Clinical presentation

        Pyrexia minimizes blood flow to the skin, giving it a pale appearance. Once body temperature rises, the skin flushes and sweats. A fever patient may lose appetite and feel lethargic, achy and sleepy.

        Metabolism increases, Blood pressure, pulse rate and cardiac output increases, Rate of respiration increases, Dehydration and fall of plasma chloride level, there occurs a negative – nitrogen balance.

Risks of pyrexia

        Very high fever ie, above 1060 F [410 C] may harm the heart and brain. Some children may have the chance for febrile Seizures.