title: Thyrotoxic periodic paralysis in a Caucasian man: recognition and diagnosis.
abstract: Periodic paralyses are uncommon disorders characterized by episodic muscle weakness, often with hypokalemia. Thyrotoxic periodic paralysis (TPP) is the most common and is rarely seen in the Caucasian population; the relative unfamiliarity of TPP among physicians in the United States may lead to initial errors in diagnosis. This article presents the case of a 25-year-old white man with frequent episodes of skeletal muscle weakness and cramping, associated with profound hypokalemia. Laboratory evaluation demonstrated primary hyperthyroidism, and a diagnosis of TPP was made. The disorder is found more commonly in men between the ages of 20 and 40. Hypokalemia is the most consistent laboratory abnormality, representing a transcellular shift rather than a total body deficit; the exact mechanism is unknown. The exercise test demonstrates distinct electromyographical abnormalities in those with periodic paralysis. The definitive treatment of TPP is establishing a euthyroid state.
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis.
authors.forename: J M
authors.initials: JM
authors.lastname: Neal
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D010243:Paralysis / Q000175:diagnosis / Q000209:etiology*; D013971:Thyrotoxicosis / Q000150:complications* / Q000175:diagnosis; D044465:White People