Thyrotoxic (hypokalemic) Periodic Paralysis

Disease Description and Diagnostic Criteria

Unfortunately, we do not understand why or how elevated thyroid function tests and thyroid hormone induce attacks in susceptible individuals.

Regarding medications, beta blockers have been found to control the condition. Acetazolamide generally makes attacks more frequent and more severe in thyrotoxic periodic paralysis (but generally makes attacks less frequent and less severe in familial hypokalemic periodic paralysis). Achieving a euthyroid state also reverses the condition. If the patient is on propylthiouracil or methimazole, then stopping these antithyroid medications will result in a hyperthyroid state. When this occurs, symptoms of periodic paralysis recur.

Any thyroid condition that causes hyperthyroidism can induce periodic paralysis in susceptible individuals. Please be certain that the cause of the hyperthyroidism is found (i.e. Grave’s disease vs. carcinoma, etc.).

A nice review on thyrotoxic periodic paralysis can be found in:
Ober, K. Patrick, “Thyrotoxic Periodic Paralysis in the United States Report of 7 Cases and Revie of the Literature.” Medicine, (1992); 71(3):109-120.

The primary cause of thyrotoxic periodic paralysis is unknown. In terms of management, the same triggers that cause attacks for familial hypokalemic periodic paralysis cause attacks for thyrotoxic periodic paralysis.
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Levitt J.  Management of Periodic Paralysis.  J Translational Medicine.