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Genetic and Rare Diseases Information Center (GARD)

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Hypokalemic periodic paralysis

Other Names for this Disease
  • HypoPP
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Tests & Diagnosis

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How is hypokalemic periodic paralysis diagnosed?

The diagnosis of hypokalemic periodic paralysis is based on a history of episodes of paralysis and low levels of potassium in the blood during attacks (less than 0.9 to 3.0 mmol/L), but not between attacks. An important part of the diagnosis is to rule out other potential causes, including myotonia, hyperthyroidism, and arrhythmia. Affected individuals typically have a family history consistent with autosomal dominant inheritance.[1]

Genetic testing is available for hypokalemic periodic paralysis. Of all individuals meeting diagnostic criteria for this condition, approximately 55 to 70 percent have mutations in the CACNA1S gene, and approximately 8 to 10 percent have mutations in the SCN4A gene. GeneTests lists the names of laboratories that perform clinical genetic testing of the CACNA1S and SCN4A genes for hypokalemic periodic paralysis. When a disease-causing mutation is identified in an affected individual, genetic testing can be performed for at-risk, asymptomatic family members.

Please note:  Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.  See below for a list of online resources that can assist you in locating a genetics professional near you.
Last updated: 4/20/2010

  1. Sternberg D, Tabti N, Hainque B, Fontaine B. Hypokalemic periodic paralysis. GeneReviews. April 28, 2009; Accessed 4/20/2010.


  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.