Analytic Review: Thyrotoxic Periodic Paralysis: A Review

Thyrotoxic periodic paralysis (TPP) is an unusual complication of hyperthyroidism that frequently presents in a dramatic fashion, necessitating treatment in an emergency department or admission to an intensive care unit. Thyrotoxic periodic paralysis is characterized by transient, recurrent episodes of flaccid muscle paralysis affecting proximal more severely than distal muscles. Thyrotoxic periodic paralysis is most commonly a complication of Graves' disease in Asian males, although in recent decades, an increasing number of patients from all racial and ethnic backgrounds have been reported. Thyrotoxic periodic paralysis has a higher predilection for men than women despite the fact that thyroid disease is more frequently diagnosed in women. The presence of both hypokalemia and elevated levels of triiodothyronine (T3) and thyroxine (T4) are important diagnostic features during the acute episode. Treatment of TPP involves 2 steps, immediate action to reverse the paralysis followed by measures to prevent future attacks by restoration of a euthyroid state. Although the mainstay of treating an acute attack of TPP is correction of hypokalemia to avoid fatal cardiac arrhythmias and reverse muscle weakness, it must be appreciated by treating physicians that patients with TPP do not have a total body deficiency of potassium. Close attention must be given to potassium replacement as overly aggressive treatment can result in hyperkalemia. Correction of hypokalemia and the underlying thyrotoxic state usually results in amelioration of the acute attack. This review summarizes the epidemiology, clinical manifestations, pathogenesis, diagnosis, and treatment of TPP.