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Hyperkalemic periodic paralysis
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Hyperkalemic periodic paralysis

Hyperkalemic periodic paralysis is a genetic condition characterized by recurring episodes of muscle weakness or paralysis triggered by factors such as potassium intake, rest after exercise, or stress.

Overview

Hyperkalemic periodic paralysis causes episodes of extreme muscle weakness or paralysis, usually beginning in infancy or early childhood. These episodes typically involve the arms and legs and may increase in frequency until mid-adulthood. Between attacks, muscle strength usually returns to normal, though some individuals experience mild stiffness (myotonia) in the face and hands.

Triggers and Symptoms

Attacks can be triggered by various factors, including:

  • Rest after exercise
  • Potassium-rich foods (e.g., bananas, potatoes)
  • Stress, fatigue, or fasting
  • Alcohol or pregnancy
  • Exposure to hot or cold temperatures
  • Certain medications

During attacks, many individuals have elevated blood potassium levels (hyperkalemia), caused by the release of potassium from weak or paralyzed muscles. In some cases, blood potassium levels remain normal (normokalemia).

Causes

The condition is caused by mutations in the SCN4A gene, which provides instructions for making a protein essential for skeletal muscle function. This protein forms sodium channels that control the flow of sodium ions into muscle cells, which is necessary for muscle contraction.

Mutations in the SCN4A gene cause these channels to stay open too long or fail to close properly. This allows excess sodium to enter muscle cells, triggering the release of potassium and further disrupting ion transport. This process reduces the ability of skeletal muscles to contract, leading to weakness or paralysis.

Inheritance

This condition is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder.

Frequently Asked Questions

Treat the episode as an emergency if you cannot stand, breathe normally, or have cardiac symptoms. Sit or lie down, avoid strenuous activity, and have a family member call emergency services. In the acute setting, physicians may give intravenous glucose, insulin, or beta‑agonists to drive potassium back into cells, and they will monitor cardiac rhythm closely.
Yes. Certain drugs such as diuretics, beta‑agonists, and some anesthetics can increase serum potassium and provoke attacks. Conversely, carbonic anhydrase inhibitors (e.g., acetazolamide) and potassium‑lowering agents (e.g., thiazide diuretics) are often prescribed to reduce attack frequency. Always review new prescriptions with your neurologist.
Diagnosis combines a clinical history of triggered weakness, serum potassium measurements during attacks, and electromyography. Definitive confirmation is achieved by sequencing the SCN4A gene to identify pathogenic variants. A positive genetic result also allows cascade testing of family members.
Small, regular servings of potassium‑containing foods are usually tolerated, but large meals or rapid intake can precipitate weakness. Many patients find it helpful to spread potassium throughout the day, avoid high‑potassium snacks on an empty stomach, and keep a food diary to identify personal thresholds.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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