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Familial periodic paralyses

Familial periodic paralyses are a group of inherited neurological disorders caused by mutations in genes that regulate sodium and calcium channels in nerve cells. They are characterized by episodes in which the affected muscles become slack, weak, and unable to contract. Between attacks, the affected muscles usually work as normal.

The two most common types are:

1. Hypokalemic periodic paralysis is characterized by a fall in potassium levels in the blood. Attacks often begin in adolescence and are triggered by:

  • Strenuous exercise
  • High carbohydrate meals
  • Injection of insulin, glucose, or epinephrine

Weakness may be mild and limited to certain muscle groups, or more severe and affect the arms and legs. Attacks may last for a few hours or persist for several days. Some people may develop chronic muscle weakness later in life.

2. Hyperkalemic periodic paralysis is characterized by a rise in potassium levels in the blood. Attacks often begin in infancy or early childhood and are precipitated by rest after exercise or by fasting. Attacks are usually shorter, more frequent, and less severe than the hypokalemic form. Muscle spasms are common.

Treatment focuses on preventing further attacks and symptom relief. Avoiding carbohydrate-rich meals and strenuous exercise and taking acetazolamide daily may prevent hypokalemic attacks. Attacks can be managed by drinking a potassium chloride oral solution. Eating carbohydrate-rich, low-potassium foods, and avoiding strenuous exercise and fasting, can help prevent hyperkalemic attacks. Dichorphenamide may prevent attacks.

Chronic attacks may result in progressive weakness that persists between attacks. Some cases respond well to treatment, which can prevent or reverse progressive muscle weakness.

How can I or my loved one help improve care for people with familial periodic paralyses?

Consider participating in a clinical trial so clinicians and scientists can learn more about familial periodic paralyses and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with familial periodic paralyses at

Where can I find more information about familial periodic paralyses?

Information may be available from the following organizations and resources:

Muscular Dystrophy Association
Phone: 800-572-1717

National Organization for Rare Disorders (NORD)

Content source: Accessed June 22, 2023.

The information in this document is for general educational purposes only. It is not intended to substitute for personalized professional advice. Although the information was obtained from sources believed to be reliable, MedLink, its representatives, and the providers of the information do not guarantee its accuracy and disclaim responsibility for adverse consequences resulting from its use. For further information, consult a physician and the organization referred to herein.

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