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Thyrotoxic periodic paralysis

Laurie Gutmann, MD
Robin Conwit, MD
Section Editor
Jeremy M Shefner, MD, PhD
Deputy Editor
Janet L Wilterdink, MD


Periodic paralysis (PP) is a muscle disease in the family of diseases called channelopathies, manifested by episodes of painless muscle weakness. These episodes may be precipitated by heavy exercise, fasting, or high-carbohydrate meals. PP is classified as hypokalemic when episodes occur in association with low potassium blood levels or as hyperkalemic when episodes can be induced by elevated potassium. Most cases of PP are hereditary, usually with an autosomal dominant inheritance pattern. Acquired cases of hypokalemic PP have been described in association with hyperthyroidism. The clinical features of these disorders are summarized in the Table (table 1).

In contrast to other forms of thyroid disease, which are more common in women, thyrotoxic PP is much more frequently seen in males; the prevalence of thyrotoxic PP is also highest in Asians [1]. This diagnosis should be considered when this demographic of patients presents with marked painless weakness after provocation with exercise or changes in diet [2].

Thyrotoxic PP will be reviewed here. Other causes of PP and other neurologic manifestations of thyrotoxicosis are discussed separately. (See "Hypokalemic periodic paralysis" and "Hyperkalemic periodic paralysis" and "Neurologic manifestations of hyperthyroidism and Graves' disease".)


Thyrotoxic PP is a sporadic form of hypokalemic PP that may occur in association with hyperthyroidism. This contrasts with familial hypokalemic PP which has an autosomal dominant inheritance.

Any etiology of hyperthyroidism, including thyroxine abuse, can be associated with thyrotoxic PP [3-7]. Graves' disease is the underlying disorder in most cases of thyrotoxic PP, as it is in most cases of hyperthyroidism [7-9]. (See "Disorders that cause hyperthyroidism".)

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Literature review current through: Nov 2017. | This topic last updated: Nov 04, 2014.
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