Body temperature is the result of a balance of heat-generating forces, chiefly METABOLISM and muscular activity, and heat-loss, mainly from blood circulation through and evaporation from the skin and lungs. Disturbance of temperature, as in disease, may be caused by impairment of any of these bodily functions, or by malfunction of the controlling centre in the brain.
In humans the ‘normal’ temperature is around 37 °C (98.4 °F). It may rise as high as 43 °C or fall to 32 °C in various conditions, but the risk to life is only serious above 41 °C or below 35 °C.
Fall in temperature may accompany major loss of blood, starvation, and the state of collapse (see SHOCK) which may occur in severe FEVER and other acute conditions. Certain chronic diseases, notably HYPOTHYROIDISM (see THYROID GLAND, DISEASES OF), may be accompanied by a subnormal temperature. Increased temperature is a characteristic of many ACUTE diseases, particularly infections. Body temperature is usually measured in the external ear canal, in the armpit, the external ear canal or (occasionally in infants) the rectum. (See also THERMOMETER.)
Abnormally low temperatures may be treated by application of external heat, or reduction of heat loss from the body surface. High temperature may be treated with medication such as paracetamol or aspirin (adults), by reducing clothing and applying a fan and by treating the underlying condition (see ANTIPYRETICS). In children between 6 months and 6 years, high temperature may provoke a FEBRILE CONVULSION. The height of the fever is a diagnostic aid in the very young as to the likelihood of an infection being bacterial, and therefore requiring antibiotics.