Overview
Thyrotoxic periodic paralysis (TPP) is a condition where episodes of sudden muscle weakness or paralysis occur in people who have too much thyroid hormone in their body (a condition called hyperthyroidism or thyrotoxicosis). During an attack, muscles — especially in the legs and arms — become very weak or completely unable to move. These episodes are caused by a sudden drop in potassium levels in the blood, which disrupts the normal electrical signals that muscles need to work. The attacks usually last from a few hours to a day and often happen at night or in the early morning hours. Common triggers include eating a large carbohydrate-rich meal, drinking alcohol, intense exercise, stress, or taking certain medications. The good news is that TPP is treatable and often reversible. The most important step is treating the underlying thyroid problem. Once thyroid hormone levels return to normal, the paralysis episodes typically stop completely. During an acute attack, potassium replacement can quickly restore muscle strength. Some people are also given a medication called propranolol to help prevent attacks while the thyroid condition is being treated. TPP is more common in men of Asian descent, though it can affect anyone with hyperthyroidism. It is sometimes also called thyrotoxic hypokalemic periodic paralysis.
Also known as:
Key symptoms:
Sudden muscle weakness or paralysis, usually in the legs and armsLow potassium levels in the blood during an attackAttacks that often happen at night or early morningMuscle weakness that can range from mild heaviness to complete inability to moveRapid or irregular heartbeat during an attackMuscle cramps or achesDifficulty climbing stairs or rising from a seated positionWeakness that usually spares the face and breathing musclesSymptoms of an overactive thyroid: weight loss, sweating, heat intolerance, tremor, rapid heartbeatEpisodes triggered by heavy carbohydrate meals, alcohol, or strenuous exercise
Clinical phenotype terms (42)— hover any for plain English
Multifactorial
Caused by a mix of several genes and environmental factors
Adult
Begins in adulthood (age 18 or older)
Treatments
No FDA-approved treatments are currently listed for Thyrotoxic periodic paralysis.
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Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Thyrotoxic periodic paralysis.
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Questions for your doctor
Bring these to your next appointment
- Q1.What is causing my hyperthyroidism, and what is the best treatment option for me?,How long will it take before my thyroid levels are normal and the paralysis attacks stop?,Should I take propranolol or potassium supplements to prevent attacks in the meantime?,What should I do — and who should I call — if I have another paralysis attack at home?,Are there specific foods, activities, or medications I should avoid to reduce my risk of an attack?,Should I be tested for the KCNJ18 gene variant, and does it change my treatment?,Once my thyroid is treated, what are the chances the paralysis episodes will come back?
Common questions about Thyrotoxic periodic paralysis
What is Thyrotoxic periodic paralysis?
Thyrotoxic periodic paralysis (TPP) is a condition where episodes of sudden muscle weakness or paralysis occur in people who have too much thyroid hormone in their body (a condition called hyperthyroidism or thyrotoxicosis). During an attack, muscles — especially in the legs and arms — become very weak or completely unable to move. These episodes are caused by a sudden drop in potassium levels in the blood, which disrupts the normal electrical signals that muscles need to work. The attacks usually last from a few hours to a day and often happen at night or in the early morning hours. Common tr
How is Thyrotoxic periodic paralysis inherited?
Thyrotoxic periodic paralysis follows a multifactorial inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Thyrotoxic periodic paralysis typically begin?
Typical onset of Thyrotoxic periodic paralysis is adult. Age of onset can vary across affected individuals.
Which specialists treat Thyrotoxic periodic paralysis?
1 specialists and care centers treating Thyrotoxic periodic paralysis are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.