What causes hyperthermia?

Updated: Oct 14, 2020
  • Author: Erik D Schraga, MD; Chief Editor: Sage W Wiener, MD  more...
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Hyperthermia is defined as elevated core temperature of greater than 38.5°C  (101.3°F). History and clinical examination can help elucidate the etiology of hyperthermia and tailor treatment. The causes of hyperthermia include the following [4] :

  • Increased ambient heat - Heat waves, humidity

  • Increased heat production - Overexertion, thyroid storm, malignant hyperthermia, neuroleptic malignant syndrome, serotonin syndrome, pheochromocytoma, delirium tremens, hypothalamic hemorrhage, toxic ingestions (eg, sympathomimetics, anticholinergics, MDMA)

  • Decreased heat dissipation - Humid environment, poor sweat production

Sweating and peripheral vasodilation are major mechanisms of heat loss to maintain proper temperature. In the absence of these mechanisms, baseline temperature would increase 1.1°C per hour from basal metabolism alone. [4] Sweat cools the body through evaporation, and peripheral vasodilation provides the blood flow and heat necessary to evaporate the sweat. During periods of high environmental heat and humidity, evaporative cooling can become insufficient, leading to heat illness.

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