Hyperthermia is a high core body temperature that exceeds the homeostatic range.
Typically, definitions state this as ≥38.0oC. Some sources state extreme hyperthermia as ≥40.0oC.
Unlike fever, which is an elevation of core body temperature above the normal range attributable to an increase in the regulatory set point (due to hypothalamic activity); hyperthermia is outside of thermoregulatory control. This is due to excess heat production or inadequate heat dissipation, or a combination of both.
