Normothermia

Normothermia is the state in which the body's core temperature remains within the normal physiologic range. In healthy adults, this range is commonly cited as about 36.5 to 37.5 degrees Celsius (97.7 to 99.5 degrees Fahrenheit), though exact values vary among individuals and measurement sites. Core temperature is regulated by the hypothalamus, balancing heat production from metabolism and activity with heat loss through the skin, respiration, and sweating. The body exhibits small fluctuations due to circadian rhythms, age, hormonal status, and environmental conditions.

In clinical practice, normothermia is often the target during surgery or critical illness. Deviations can have adverse effects: hypothermia increases cardiovascular strain and bleeding risk, while hyperthermia or fever can raise metabolic demand and worsen outcomes in infection or brain injury. Perioperative or therapeutic strategies may include warming or cooling measures to maintain or restore normothermia.

Measurement of core temperature is most accurate with esophageal, rectal, bladder, or core-cavity monitoring. Peripheral sites such as oral, tympanic, or skin temperatures can be influenced by ambient conditions and may lag behind true core temperature, especially during rapid changes.

Normothermia is distinct from fever, hyperthermia, and hypothermia, and represents a stable, regulated state of body temperature. Maintaining normothermia is particularly emphasized in anesthesia, critical care, neonatology, and situations where temperature deviations can impact outcomes.