When a person’s body temperature is not within the normal temperature range, the cause is usually an infection or a dangerous environmental condition.

a. Infection.

An infection occurs when the body is invaded by harmful microorganisms. When an infection occurs, the body attempts to destroy the invading microorganisms. One method used by the body is raising the body’s temperature to a point where the invading microorganisms will be weakened or destroyed. When a person has a body temperature above his normal body temperature, he is said to have a fever. Another name for fever is pyrexia. Pyrexia comes from the Greek word “pyr,” which means “on fire.”

b. Environmental Conditions.

Even though the body can maintain a normal body temperature under most weather conditions, very hot or very cold conditions can cause the hypothalamus to work improperly.

(1) Heatstroke. Sometimes the body cannot get rid of body heat fast enough and the body temperature rises. This condition is most likely to happen when a person is performing hard work in a hot climate. The rising body temperature is too much for the hypothalamus to handle and it begins to lose control of the body’s cooling mechanisms. When the body stops perspiring, the body temperature continues to rise. This condition is known as heatstroke. The person will usually lose consciousness. Rapid cooling of the body is essential in the preventing major organ damage and death in the heatstroke patient.

(2) Generalized hypothermia. Generalized hypothermia refers to the lowering of the body temperature below normal levels. Death will result if the body temperature is not restored. For example, suppose a person falls off a ship into cold ocean water. The body looses heat to the cold water faster than the body can produce heat. If the person is removed from the cold conditions (pulled out of the water onto a boat, for example), the body may not be able to warm itself. In such a case, an outside source of heat (such as another person lying body to body with the victim) is needed to restore normal body temperature to the victim until the hypothalamus is functioning properly again. The body must be warmed slowly and in a controlled environment to prevent overwhelming of the body’s system.