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Hyperkalemic Form of Familial Periodic Paralysis

Hyperkalemic Form of Familial Periodic Paralysis

What is periodic paralysis syndrome? — Periodic paralysis syndrome is a rare condition that causes sudden episodes of muscle weakness. These episodes are brought on by certain things, such as:
Heavy exercise
Eating a lot of carbohydrates – Carbohydrates are sugars and starches that are in food.
Not eating for long periods of time
Very cold air
There are different types of periodic paralysis, depending on the cause. The different types are:
Hypokalemic – "Hypokalemia" is the medical term for low levels of potassium in the blood. Potassium is a salt that cells need to work normally. Too much or too little potassium can cause problems. Hypokalemic periodic paralysis happens when there is too little potassium in the body.
Hyperkalemic – "Hyperkalemia" is the medical term for high levels of potassium in the blood. Hyperkalemic periodic paralysis usually happens when there is too much potassium in the body.
Thyrotoxic – This is a type of hypokalemic periodic paralysis, but it is caused by a condition called hyperthyroidism. In hyperthyroidism, a gland called the thyroid is overactive and makes too much thyroid hormone (figure 1).
Except in rare cases, people who have periodic paralysis are born with it. The condition is caused by an abnormal gene and usually runs in families.
What are the symptoms of periodic paralysis syndrome? — Most people with periodic paralysis first have symptoms in early childhood. In general, periodic paralysis causes sudden episodes of muscle weakness that affect the whole body. These episodes do not make people black out or lose consciousness.
Hypokalemic periodic paralysis episodes usually happen once every few weeks or months. Each episode usually lasts a few hours, but an episode can last for days.
Hyperkalemic periodic paralysis episodes usually happen more often, sometimes every day. But each episode is not usually as severe and does not usually last as long.
Some patients with periodic paralysis develop a permanent muscle weakness that slowly gets worse over time. When this happens, it is usually later in life.
Will I need tests? — It depends on whether the condition is known to run in your family. If the condition runs in your family, you probably won't need any tests.
If the condition isn't known to run in your family, your doctor will order tests. He or she will try to have the tests done when you are having symptoms. Tests that are commonly done include:
Blood tests
An electrocardiogram (also called an "ECG") – This test measures the electrical activity in your heart (figure 2). Too little or too much potassium in the body can affect the heart.
Electromyography (also called "EMG") – This test shows how well a person's nerves and muscles are working.
How is periodic paralysis syndrome treated? — Periodic paralysis is treated in different ways.
Some treatments can help stop or shorten episodes of muscle weakness. Hypokalemic periodic paralysis episodes are treated with potassium that people take by mouth. This treatment helps raise the level of potassium in the body to a normal level.
Hyperkalemic periodic paralysis episodes do not always need treatment, because they usually last for a short time only. But they are sometimes treated with medicines that lower the level of potassium in the body.
Other treatments can help prevent episodes of periodic paralysis from happening. These include lifestyle changes and medicines.
Lifestyle changes that can help prevent episodes:
Avoiding heavy exercise
Eating a diet that is low in carbohydrates
Avoiding foods with high levels of potassium, if you have hyperkalemic periodic paralysis (table 1)
If these lifestyle changes don't help enough, your doctor will talk with you about taking a daily medicine to help prevent symptoms. The medicine your doctor prescribes will depend on the type of periodic paralysis you have.
What else should I do if I have periodic paralysis syndrome? — Be sure to let your other doctors and nurses know that you have this condition. That way, if you ever have a procedure or surgery, the doctor can make sure your potassium level doesn't get too low or too high. Doctors might also avoid giving you medicines that affect your potassium level.
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Mar 30, 2020.
Topic 83672 Version 6.0
Release: 28.2.2 - C28.105
© 2020 UpToDate, Inc. and/or its affiliates. All rights reserved.

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