Thyrotoxic Periodic Paralysis as an Initial Manifestation of Hyperthyroidism in a Young Male Patient

Thyrotoxic periodic paralysis (TPP) is a rare but potentially fatal complication of hyperthyroidism, characterized by acute muscle weakness and hypokalemia. Although most frequently described in Asian populations, it can occur in other ethnic groups and is often underdiagnosed. We present the case of a 21-year-old Mexican man with acute lower-extremity weakness. Initial laboratory evaluation revealed a serum potassium level of 2.7 mEq/L and biochemical thyrotoxicosis. The patient received 60 mEq of intravenous potassium chloride over six hours, with complete recovery of muscle strength approximately eight hours after treatment initiation, supporting the diagnosis of TPP. Thyroid scintigraphy was suggestive of diffuse toxic goiter, while the elevated thyrotropin receptor antibody (TRAb) level supported Graves' disease as the underlying etiology. This case highlights the importance of considering TPP in the differential diagnosis of acute flaccid paralysis and emphasizes the need for early diagnosis and treatment to prevent potentially serious complications.