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Malignant Hyperthermia

It is possible that the main title of the report Malignant Hyperthermia is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Hyperpyrexia

Disorder Subdivisions

  • None

General Discussion

Malignant hyperthermia (MH) is a dominantly inherited disorder of skeletal muscle that predisposes susceptible individuals to a life threatening adverse reaction (fulminant MH event) upon exposure to potent volatile anesthetics (halothane, isoflurane, sevoflurane, desflurane, etc.) and the skeletal muscle relaxant succinylcholine.

The anesthetic drugs trigger an uncontrolled calcium (Ca2+) release from the sarcoplasmic reticulum (SR) through the ryanodine receptor (RYR1) causing a rapid and sustained rise in myoplasmic Ca2+. The high intracellular Ca2+ activates Ca2+ pumps at the SR and the sarcolemma to reuptake calcium into SR or to transport it into the extracellular space respectively. The energetic cost to regain cellular Ca2+ control causes a need for ATP, which in turn produces heat. Muscle membrane integrity is compromised leading to hyperkalemia and rhabdomyolysis.1 If not treated promptly, by withdrawing the anesthetic and administering dantrolene, mortality can be greater than 70%.2 In some individuals, fulminant MH events can be induced by stress, exercise and high environmental temperatures in the absence of anesthetics.3 Pediatric patients may be at greater risk.4


Malignant Hyperthermia Association of the United States
1 North Main St
PO Box 1069
Sherburne, NY 13460
Tel: (607)674-7901
Fax: (607)674-7910

North American Malignant Hyperthermia Registry
Penn State University
Dept. of Anesthesiology
P.O. Box 850
Hershey, PA 17033-0850
Tel: (412)692-6390
Fax: (412)692-8658
Tel: (888)274-7899

NIH/National Institute of General Medical Sciences
45 Center Drive MSC 6200
Bethesda, MD 20892-6200
Tel: (301)496-7301
Fax: (301)402-0224

Malignant Hyperthermia Investigation Unit
Toronto General Hospital
200 Elizabeth Street
CCRW-2, Room ES3-403A
Ontario, M5G 2C4
Tel: 4163403128
Fax: 4163404960

Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311
TDD: (888)205-3223

Neuroleptic Malignant Syndrome Information Service, Inc.
PO Box 1069
11 East State Street
Sherburne, NY 13460
Tel: (607)674-7920
Fax: (607)674-7910

For a Complete Report:

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated: 6/27/2013
Copyright 1984, 1988, 1989, 1990, 1992, 1999, 2005, 2009, 2013 National Organization for Rare Disorders, Inc.

WebMD Medical Reference from the National Organization for Rare Disorders

Last Updated: May 28, 2015
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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