Which statement correctly differentiates heat stroke from heat exhaustion?

• A. Heat exhaustion is characterized by core body temperature above 104 F.
• B. Heat stroke is a result of dehydration without altered mental status.
• C. Heat stroke involves failure of the body's thermoregulation.
• D. Heat exhaustion requires rapid cooling.

Answer: (C)

Thermoregulatory failure is the key difference between heat stroke and heat exhaustion. Heat stroke happens when the body's heat-dissipating mechanisms fail, so core temperature climbs rapidly and the patient often has altered mental status or other CNS dysfunction. That combination—very high temperature with CNS impairment—is what distinguishes heat stroke, and the statement that heat stroke involves failure of the body's thermoregulation captures this mechanism best.

Heat exhaustion, on the other hand, results largely from dehydration and volume depletion with preservation or only mild impairment of thermoregulation; patients may be fatigued, dizzy, and sweaty, with a lower risk of CNS changes and typically not the same extreme core temperatures. Rapid cooling is most critical in heat stroke, whereas heat exhaustion is mainly treated with fluids and rest, so that emphasis in another option doesn’t fit as the defining difference.