Graves' Disease With Initial Presentation of Thyrotoxic Periodic Paralysis

Graves' disease is a common cause of hyperthyroidism. However, thyrotoxic periodic paralysis (TPP) is a rare complication of Graves' disease and is characterized by episodes of muscle weakness and hypokalemia in the setting of thyrotoxicosis. Episodic weakness and paralysis can be the first manifestation of Graves' disease with TPP despite lacking classic symptoms of hyperthyroidism and can be precipitated by risk factors such as a high carbohydrate diet and strenuous exercise. Although TPP is reversible with correction of hypokalemia and thyrotoxicosis, its uncommon presentation can lead to delay in diagnosis and treatment. Here, we describe a case of a 24-year-old Thai male who presented with proximal muscle weakness that progressed to frequent falls and inability to ambulate over the course of three days. He was found to have severe hypokalemia and diagnosed with TPP from underlying Graves' disease. He was treated with cautious replacement of potassium, a beta blocker, and methimazole to reverse thyrotoxicosis. He regained his ability to ambulate, and his weakness resolved after hypokalemia was corrected. He did not have a reoccurrence of muscle weakness the following 12 months after discharge by continuing treatment with methimazole. The varied clinical manifestations of TPP can make diagnosis challenging, but early recognition and treatment can prevent severe complications of this potentially life-threatening condition.