Thyrotoxic hypokalemic periodic paralysis is rare, especially in Caucasians. Affected patients have muscle weakness secondary to hypokalemia associated with hyperthyroidism. We report the case of a 23-year-old patient who was admitted to the emergency department for sudden-onset tetraparesis without any trauma. Tetraparesis was accompanied by severe hypokalemia. Etiologic investigations have led to the diagnosis of Graves' disease. Hypokalemic periodic paralysis is a rare neuromuscular complication of hyperthyroidism. It originates from hypokalemia secondary to intracellular transfer caused by both Na+/K+ ATPase pump overstimulation and abnormal potassium efflux due to a mutation in the potassium efflux channel. The clinical management consists in conservative potassium supplementation and administration of ß-blockers. The neuromuscular deficit is transient and reverses rapidly after the correction of hyperthyroidism.
Periodic paralysis, hypokalemia, Graves' disease, thyrotoxic hypokalemic periodic paralysis