Thyrotoxic periodic paralysis
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Definition
Thyrotoxic periodic paralysis is a condition in which there are episodes of muscle weakness in people with high levels of thyroid hormone (hyperthyroidism, thyrotoxicosis).
Alternative Names
Periodic paralysis - thyrotoxic
Causes, incidence, and risk factors
Thyrotoxic periodic paralysis is a rare condition that occurs only in people with high thyroid hormone levels (thyrotoxicosis). It is seen most commonly in Asian men.
There is a similar disorder, hypokalemic periodic paralysis (familial periodic paralysis). This is an inherited condition and does not have high thyroid levels.
Risk factors include a family history of periodic paralysis and hyperthyroidism.
Review Date: 4/20/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Periodic paralysis - thyrotoxic
Symptoms
Thyrotoxic periodic paralysis involves attacks of muscle weakness or paralysis alternating with periods of normal muscle function. Attacks usually begin after symptoms of hyperthyroidism have developed.
The frequency of attacks varies from daily to yearly. Episodes of muscle weakness may last for a few hours or several days.
Symptoms include:
- Difficulty breathing (rare)
- Speech difficulty (rare)
- Swallowing difficulty (rare)
- Vision changes (rare)
- Weakness/paralysis
- Comes and goes
- Lasts for up to several days
- More common in legs than arms
- Most common in shoulders and hips
- Triggered by heavy, high-carbohydrate, high-salt meals
- Triggered by rest after exercise
People are alert during attacks. Normal strength returns between attacks.
Symptoms of hyperthyroidism:
Signs and tests
The health care provider may suspect thyrotoxic periodic paralysis based on:
Diagnosis involves ruling out disorders associated with low potassium.
The health care provider may attempt to trigger an attack by giving you insulin and glucose (which reduces potassium levels) or thyroid hormone.
During an attack, there may be the following signs:
Low potassium in the bloodstream (
serum potassium levels are normal between attacks)
- Weakness, especially in the muscles of the arms and legs and occasionally in the muscles of the eyes. The muscles involved in breathing and swallowing can sometimes be affected, and this can be fatal. Muscle strength is normal between attacks at first. However, repeated attacks may eventually cause worsening and persistent muscle weakness.
Between attacks, examination is normal. Or, there may be signs of hyperthyroidism, such as an enlarged thyroid.
Hyperthyroidism is confirmed by abnormal results on the following tests:
Other test results:
- Abnormal ECG (electrocardiogram) during attacks
- Abnormal EMG (electromyogram) during attacks
- Low serum potassium during attacks, but normal between attacks
A muscle biopsy may occasionally show abnormalities.
Review Date: 4/20/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Periodic paralysis - thyrotoxic
Treatment
The best treatment is to quickly reduce thyroid hormone levels. Potassium should also be given during the attack, preferably by mouth. If weakness is severe, intravenous potassium may be needed. (Note: intravenous potassium should be given only if kidney function is normal and the patient is monitored in the hospital.)
Weakness that involves the muscles used for breathing or swallowing is an emergency. Patients must be taken to a hospital. Dangerous heart arrhythmias may also occur during attacks.
Your health care provider may recommend that you eat a diet low in carbohydrates and salt to prevent attacks. Medications called beta blockers may reduce the number and severity of attacks while hyperthyroidism is brought under control.
Acetazolamide is effective in preventing attacks in people with familial periodic paralysis. It is usually not effective with thyrotoxic periodic paralysis.
Expectations (prognosis)
Chronic attacks will eventually lead to muscle weakness that persists even between attacks. Thyrotoxic periodic paralysis responds well to treatment. Treating hyperthyroidism will prevent attacks and may even reverse muscle weakness.
Complications
- Difficulty breathing, speaking, or swallowing during attacks (rare)
- Heart arrhythmias during attacks
- Muscle weakness that gets worse over time
Calling your health care provider
Go to the emergency room or call the local emergency number (such as 911) if you have periods of muscle weakness. This is especially important if you have a family history of periodic paralysis or thyroid disorders.
Emergency symptoms include:
Difficulty breathing, speaking, or swallowing
Fainting
Review Date: 4/20/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Periodic paralysis - thyrotoxic
Prevention
Genetic counseling may be advised. Treating the thyroid disorder prevents attacks of weakness.
Review Date: 4/20/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Review Date: 4/20/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.