Skip to main content Skip to Search Box

Definition: hypothermia from Collins English Dictionary


1 pathol an abnormally low body temperature, as induced in the elderly by exposure to cold weather

2 med the intentional reduction of normal body temperature, as by ice packs, to reduce the patient's metabolic rate: performed esp in heart and brain surgery

Summary Article: Hypothermia
From Encyclopedia of Global Health

Hypothermia refers to when the body’s temperature falls below a temperature necessary to maintain normal metabolic functions. The normal body temperature is 37 degrees C and hypothermia occurs when the body drops to below 35 degrees C. Nearly 700 people die each year from hypothermia in the United States.

There are many causes of hypothermia such as decreased heat production. This can be because of endocrine abnormalities such as hypopituitarism or hypothyrodism. Decreased heat production can also be due to hypoglycemia or malnutrition. It is important to consider these causes of hypothermia when a person’s normal body temperature does not rise through treatment, such as blankets and warming. Another cause of hypothermia can be due to increased heat loss. There are many factors that can lead to this cause, such as immersion in a cold body of water, or being in cold weather without sufficient clothing. Another common cause of increased heat loss is due to alcoholic intoxication. Alcohol causes cutaneous vasodilation of arteries which warms the skin. Core body temperature decreases due to shunting of blood to the periphery and leads to hypothermia. Finally, another cause of hypothermia is impaired thermoregulation which is caused by failure of the hypothalamus to regulate body temperature. At-risk populations for hypothermia are elderly adults, children, and mentally impaired individuals.

Hypothermia occurs when the body drops to below 35 degrees Celsius and kills nearly 700 people per year in the United States.

Different publications have different criteria to determine mild, moderate, and severe hypothermia. In general, mild hypothermia begins when the temperature of the body falls below 35 degrees C but is still above 32 degrees C. The person will show signs of shivering, pale blue skin, slurring speech, confusion, and respiratory rate may increase. Moderate hypothermia occurs when body temperature is between 28 to 32 degrees C. Patients present in a stupor, they usually are not shivering anymore, body becomes rigid, and breathing becomes shallower. Severe hypothermia occurs when the body temperature is below 28 degrees C. Symptoms of severe hypothermia include difficulty breathing, unconsciousness, no pulse, and extreme rigidity. Patients with severe hypothermia also have an increased risk for ventricular arrhythmias, which can be life threatening.

There are many tests and observations that can be done that will tell if a person is hypothermic. If the person can voluntarily stop his or her shivering then he or she most likely has mildly hypothermic. Another test is to ask the patient to count backward from 100 by a certain multiple, such as six. This requires higher reasoning by the brain and if the person is hypothermic they will not be able to accomplish this task. Another test is to check the radial pulses. If the person has a very faint or no radial pulse, then they are most likely severely hypothermic.

Treatment for patients with hypothermia is to slowly warm the body back to normal body temperature. Remove the person from the external stimulus that may be causing the hypothermia, such as cold water. Also provide warm beverages for the person to drink and monitor his or her breathing. Do not apply direct heat to a person that is hypothermic, such as a heating pad or warm water. If a heating pad is placed on the arm or legs, then cold blood will get shunted to the core and can lead to complications. Also do not massage the body of the person who is hypothermic. Individuals who are hypothermic are at an increased risk for cardiac complications and so massaging the body can exacerbate this risk. In the hospital, doctors will treat hypothermia differently based on the severity and cause. In general, doctors will use blankets and external actions to warm the body. If the patient is severely hypothermic, the doctor may infuse warm fluids into the person or have the person placed on hemodialysis. Most people with hypothermia recover without any long-term complications.

  • Alcoholism; Alcohol Consumption; Alzheimer’s Disease; Parkinson’s Disease; Hypopituitarism; Hypothyroidism.

  • Rick Curtis, “Outdoor Action Guide to Hypothermia and Cold Weather Injuries,” (cited November 2007).
  • Hypothermia,” (cited December 2006).
  • Hypothermia,” (cited January 2007).
  • Vinay Kumar, et al., Pathologic Basis of Disease (Elsevier Saunders, 2005).
  • Pavan Bhatraju
    University of Louisville
    Copyright © 2008 by SAGE Publications, Inc.

    Related Articles

    Full text Article hypothermia
    Cambridge Dictionary of Human Biology and Evolution

    Any decrease in body temperature , regardless of cause. In adult humans, the mild hypothermia threshold is =36 °C (oral); the severe...

    Full text Article normothermia
    Collins Dictionary of Medicine

    A body temperature within normal limits. The term is used mainly in contexts in which hypothermia is a possibility or a risk. ...

    Full text Article Hyperthermia/Hypothermia Unit Management
    Gale Encyclopedia of Nursing and Allied Health

    Definition Hyperthermia/hypothermia unit management is the use of special electronically regulated blankets or pads to adjust body temperature un

    See more from Credo