Hypokalemic Periodic Paralysis In A Patient With Euthyroid Graves Disease And Celiac Disease

ABSTRACT Objective: Thyrotoxic periodic paralysis is a sporadic form of hypokalemic periodic paralysis (HPP) that is most commonly seen in patients with Graves disease (GD) in association with acute thyrotoxicosis. A very few cases of HPP have been reported in patients with GD while the patient was euthyroid. Methods: We describe a case of a 62-year-old Caucasian male with a history of GD, who presented with acute progressive bilateral lower extremity weakness. Results: The patient was found to have severe hypokalemia, with no evidence of diarrhea or increased urinary potassium excretion. He was diagnosed as having HPP. He remained clinically and biochemically euthyroid during the admission. There was no history of high-carbohydrate meal intake, intense exercise, recent steroid exposure, or unusual stress. His symptoms improved gradually over the next 3 to 4 days with potassium supplementation. Nine months later, he progressed to overt hyperthyroidism and was treated with 25 mCi of iodine-131 and following that he has been on levothyroxine replacement for post-ablative hypothyroidism. Other unusual features in this patient were hypocalcemia, hypomagnesemia, and vitamin D deficiency during the acute presentation. Serum calcium and magnesium normalized 2 days after admission, while serum vitamin D continued to be low. He was later diagnosed to have celiac disease. Conclusion: Our case adds a rare presentation of HPP in a euthyroid patient with a known history of GD with associated celiac disease, hypomagnesemia, and hypocalcemia to the literature. Abbreviations: FT3 = free triiodothyronine; FT4 = free thyroxine; HPP = hypokalemic periodic paralysis; MMI = methimazole; TPP = thyrotoxic periodic paralysis; TSH = thyroid-stimulating hormone; TSI = thyroid-stimulating immunoglobulin