Sudden periodic paralysis: rare manifestation of thyrotoxicosis.

Nonfamilial hypokalemic thyrotoxic periodic paralysis is rarely diagnosed among Caucasians and blacks in the western world but it is relatively common among Asiatics. Sudden paralysis occurring while at rest after a large carbohydrate meal or strenuous exercise in an undiagnosed mild thyrotoxic patient is a common presentation. A case illustrating such presentation is reported. Intracellular shifts of potassium triggered or facilitated by hyperthyroidism and hyperinsulinemia are the biochemical features. Correction of the thyrotoxic state is the definitive treatment for this disorder. Judicious administration of potassium is indicated during the hypokalemic episode to prevent life-threatening arrhythmias.