Rebound Hyperkalemia in Hypokalemic Thyrotoxic Periodic Paralysis

<b>Background:</b> Thyrotoxic periodic paralysis (TPP) is a rare, life-threatening, reversible condition, in which episodic muscle weakness occurs due to low serum potassium in the setting of thyrotoxicosis. In addition to treating thyrotoxicosis, prompt restoration of potassium levels is essential while monitoring for rebound hyperkalemia. <b>Purpose:</b> To emphasize the importance of recognizing and appropriately managing TPP, with a focus on the potential dangers of potassium overcorrection. <b>Case Report:</b> We present a patient with TPP whose potassium replacement therapy caused dangerous hyperkalemia, requiring aggressive potassium shifting and wasting therapies and vasopressor support. <b>Conclusions:</b> This case report highlights the importance of prompt recognition and treatment of TPP as well as the need for careful management of potassium levels to prevent respiratory failure and cardiac arrhythmias. We discuss the challenges associated with potassium repletion in thyrotoxicosis including the importance of careful monitoring and titration of potassium replacement therapy to avoid overcorrection and hyperkalemia.