Summary: Thyrotoxic periodic paralysis (TPP) is a rare complication of hyperthyroidism triggered by precipitants that increase the activity of the sodium-potassium pump in the skeletal muscle. In our case study, a previously healthy 34-year-old male presented to the emergency department with new onset thyrotoxicosis, secondary to Graves' disease. Given the severity of his triiodothyronine (T3) thyrotoxicosis, he was admitted and started on a high dose of beta-blocker, thioamides, and intravenous hydrocortisone. On the second day of his hospitalization, he developed acute flaccid paralysis of his lower extremities. Subsequent stroke workup was negative, and his electrolytes revealed severe hypokalemia and hyperglycemia consistent with TPP. He was treated with potassium and had a complete recovery of his paralysis and hypokalemia within hours. The patient has not had any recurrence since this singular episode in the hospital. This case highlights the scenario where the treatment of hyperthyroidism with high-dose corticosteroids to reduce the conversion of thyroxine to T3 inadvertently resulted in TPP. Clinicians should be aware of this potentially rare but serious consequence of using steroids to manage hyperthyroidism.
Learning points: High-dose steroids used to treat hyperthyroidism in hospitalized patients may rarely precipitate thyrotoxic periodic paralysis (TPP) by inducing hypokalemia and hyperglycemia. TPP should be included in the differential diagnosis for acute flaccid paralysis in hospitalized patients with hyperthyroidism. Since TPP is associated with trans-cellular shifts in potassium instead of total body potassium depletion, conservative repletion of potassium is recommended to avoid rebound hyperkalemia.