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Hypo- and hyperthermia

Author: Lindsey Harle, M.D. (see Reviewers page)
Revised: 16 August 2012, last major update August 2012
Copyright: (c) 2012, PathologyOutlines.com, Inc.


● Core body temperature below 95° F (35° C)
● Usually due to environmental exposure
● Increased risk in very young and very old, thin individuals, males (due to decreased subcutaneous fat)
● Cold water exposure more rapidly fatal than cold air exposure, because water rapidly dissipates heat

Physiological response to cold exposure:
● Superficial vasoconstriction
● Shivering
● Increased cellular metabolism (to produce heat); more efficient in infants due to “brown fat”
● When compensatory mechanisms fail, body temperature falls linearly

Autopsy findings:
● No specific findings in hypothermia; it is a diagnosis of exclusion
● Cherry red lividity: due to accumulation of oxyhemoglobin in tissues; nonspecific (also seen in CO poisoning)
● If individual survives for a period of time, may show hemorrhagic pancreatitis, mucosal ulceration of GI tract, pneumonia, acute tubular necrosis, cardiomyocyte necrosis
● Paradoxical undressing: terminal hallucinations lead the individual to feel overheated despite the cold environment, causing them to undress


● Core body temperature above 105° F (40.5° C)
● Heat stroke is severe form
● Occurs when body’s mechanisms of dissipating heat are overwhelmed
● Risk factors: alcoholism, atherosclerosis, obesity, certain drugs (tricyclic antidepressants, some tranquilizers, monoamine oxidase inhibitors)
● Symptoms: hyperthermia, hot and dry skin, CNS dysfunction
● Vasodilation occurs, leading to circulatory failure
● If individual survives for a period of time, may develop pneumonia, acute tubular necrosis, adrenal hemorrhage, liver and myocardial necrosis, and DIC
● Autopsy findings: nonspecific; diagnosis is made based on scene investigation and antemortem signs and symptoms

More mild forms include heat cramps and heat exhaustion:
● Heat cramps: due to salt depletion; skin is moist and cool, body temperature is normal
● Heat exhaustion: due to salt and water depletion; headache, nausea/vomiting, dizziness, weakness, cramps; body temperature is normal or slightly elevated

End of Forensics > Hypo- and hyperthermia

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