What is the primary temperature threshold defining heat stroke?

The primary temperature threshold defining heat stroke is a core temperature of 104.9 degrees F or higher. Heat stroke is a serious condition that occurs when the body becomes unable to regulate its temperature, leading to a rapid increase in core body temperature. This high temperature causes cellular damage and disrupts the normal functioning of major organ systems.

In the case of heat stroke, the body's temperature regulation fails, and the body temperature can rise to dangerously high levels, often exceeding 104 degrees F. This threshold is critical, as it signifies a point at which the risk of serious complications, including organ failure and death, increases significantly. Thus, recognizing this hallmark temperature is essential in diagnosing and managing heat stroke effectively.

Other temperature ranges provided in the options do not indicate heat stroke. For instance, a core temperature below 100 degrees F, or temperatures between 98.6 and 100 degrees F, do not indicate an emergency. Similarly, while a core temperature exceeding 101 degrees F suggests heat-related illness, it does not reach the critical threshold needed for a diagnosis of heat stroke.