Fever

Fever is the natural response to infection. Pyrexia Pyrexia refers to an increase in body temperature resulting in a fever. A person with a fever is said to be febrile. When the body temperature is not raised the person is described as being apyrexial (the prefix ‘a’ or ‘an’ always means without). It is the hypothalamus which regulates body temperature by comparing the temperature of the blood circulating through the structure with a set point, usually between . When blood temperature drops, the hypothalamus initiates mechanisms to increase body temperature; conversely when blood temperature rises above the set point, heat loss mechanisms are initiated. In a fever the set point is increased to a new higher setting. Cause of fevers Fevers are most commonly caused by infection but also occur after tissue damage which may be caused by trauma, surgery or disease processes. For example, pyrexia is not uncommon after a myocardial infarction when part of the myocardium is damaged by an occlusion of the coro