Hyperpyrexia is an excessive and unusual elevation of set body temperature greater than or equal to 41.1° Celsius (106°F), or extremely high fever. It differs from hyperthermia in that the body's temperature regulation mechanism sets the body temperature too high, whereas in hyperthermia the body temperature is too high above the set point.
Differential Diagnosis of Causes of Hyperpyrexia
- excessive exposure to heat or the sun (also called heat hyperpyrexia, a part of heatstroke)
- amphetamine or other stimulant abuse, which can aggravate the effects of heat hyperpyrexia
- withdrawal from barbiturates, alcohol, or other anxiolytics, although it is less common with benzodiazepines
- septicemia (a generalized bacterial infection of the blood)
- some viral infections, such as mononucleosis
- a thyrotoxic crisis (in hyperthyroidism)
- Malignant hyperpyrexia is a particular condition caused by the breakdown of muscle following its over-excitation, in response to certain stimuli, such as extreme exercise (especially in a high ambient temperature), intense and prolonged convulsions, anesthesia, fever or some drugs, such as cocaine, alcohol and aspirin.
- Neuroleptic malignant syndrome (NMS) can also cause hyperprexia after the administration of antipsychotic drugs.
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- Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:77 ISBN 1591032016
- Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:68 ISBN 140510368X