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Alternative NamesPeriodic paralysis - hypokalemic
Definition Return to top
Hypokalemic periodic paralysis is an inherited disorder that causes occasional episodes of muscle weakness.
It is one of a group of genetic disorders that includes hyperkalemic periodic paralysis and thyrotoxic periodic paralysis.
Causes Return to top
Hypokalemic periodic paralysis is a condition in which a person has episodes of muscle weakness and sometimes severe paralysis.
The condition is congenital, which means it is present from birth. In most cases, it is passed down through families (inherited) as an autosomal dominant disorder. That means only one parent needs to pass the gene related to this condition onto you in order for you to be affected. Ocassionally, the condition may be the result of a genetic problem that is not inherited.
Unlike other forms of periodic paralysis, persons with this type have normal thyroid function and very low blood levels of potassium during episodes of weakness.
Risks include having other family members with periodic paralysis. The risk is slightly higher in Asian men who also have thyroid disorders.
Disorders that cause intermittent episodes of paralysis as their primary effect are uncommon. Hypokalemic periodic paralysis occurs in approximately 1 out of 100,000 people.
Symptoms Return to top
The disorder involves attacks of muscle weakness or loss of muscle movement (paralysis) that come and go. There is normal muscle strength between attacks.
Attacks usually begin in adolescence, but they can occur before age 10. Attacks that do not begin until adulthood are rare and are usually caused by other disorders.
How often the attacks occur varies. Some people have attacks every day, while others have them once a year. Episodes of muscle weakness usually last between a few hours and a day.
The weakness or paralysis:
Other symptoms may include:
Note: The patient's thinking remains alert during attacks.
Exams and Tests Return to top
Between attacks, a physical examination shows nothing abnormal. Before an attack there may be leg stiffness or heaviness in the legs.
A serum potassium blood tests done during an attack of muscle weakness will reveal low potassium levels. This confirms the diagnosis. There is no decrease in total body potassium, and blood potassium levels are normal between attacks.
During an attack, muscle reflexes may be decreased or absent and muscles go limp rather than staying stiff. The muscle groups near the body, such as shoulders and hips are involved more often than the arms and legs.
Treatment Return to top
Muscle weakness that involves the breathing or swallowing muscles is an emergency situation. Dangerous heart arrhythmias may also occur during attacks.
The goals of treatment are relief of symptoms and prevention of further attacks.
Potassium that is given during an attack may stop the attack. It is preferred that potassium be given by mouth, but if weakness is severe, potassium may need to be given through a vein (IV). Note: intravenous potassium should be given with caution, especially in individuals with kidney disease.
Taking potassium will not prevent attacks.
Avoiding alcohol and eating a low-carbohydrate diet may help.
A medicine called acetazolamide prevents attacks in many cases. If you take this medicine, your doctor may tell you to also take potassium supplements. Acetazolamide may cause the body to lose potassium.
Triamterene or spironolactone may help to prevent attacks in people who do not respond to acetazolamide.
Outlook (Prognosis) Return to top
Hypokalemic periodic paralysis responds well to treatment. Treatment may prevent, and even reverse, progressive muscle weakness. Although muscle strength is initially normal between attacks, repeated attacks may eventually cause worsening and permanent muscle weakness between attacks.
Insulin levels may affect the course of the disorder in some people because insulin increases the flow of potassium into cells.
Possible Complications Return to top
When to Contact a Medical Professional Return to top
Call your health care provider if you have intermittent muscle weakness, particularly if there is a family history of periodic paralysis.
Go to the emergency room or call the local emergency number (such as 911) if you faint or have difficulty breathing, speaking. or swallowing. These are emergency symptoms.
Prevention Return to top
Hypokalemic periodic paralysis cannot be prevented. Because it can be inherited, genetic counseling may be advised for couples at risk for the disorder.
Treatment prevents attacks of weakness. Before an attack there may be leg stiffness or heaviness in the legs. Performing mild exercise when these symptoms start may help prevent a full blown attack.Update Date: 7/11/2008 Updated by: Parul Patel, MD, Private Practice specializing in Nephrology and Kidney and Pancreas Transplantation, Affiliated with California Pacific Medical Center, Department of Transplantation, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.