Thyrotoxic Periodic Paralysis Presenting with Hypokalemia: A Case Report

Abstract

Background: Thyrotoxic periodic paralysis (TPP), a serious complication of hyperthyroidism, is a common etiology of secondary hypokalemic periodic paralysis (HPP). In this study, we present a case report of a patient who presented to our ED with weakness and hypokalemia and was found to have severe hyperthyroidism.Case presentation: A 29-year-old Chinese man presented to our Emergency Department complaining of feeling very weak and tired for 8 hours. The weakness was limited to his four limbs. On physical examination, he was conscious and oriented to place, persons, and time. Upper and lower limb exams showed a power of 4/5 with normal sensation and an absence of Babinski signs. The initial blood work was normal, except for mild hypokalemia; therefore, the initial plan was to start him on one liter of IV normal saline mixed with 40 mEq KCl over 4 hours before repeating the laboratory investigations. The repeated blood work showed a drop in his potassium level to 2.2 mmol/L, indicating the need for further potassium replacement and extensive blood work, including a thyroid function test, which showed severe hyperthyroidism. The patient was admitted to the critical care unit, where his vital signs were monitored continuously, and he received KCl replacement and began propranolol and carbimazole treatment.Conclusions: TPP should be a differential diagnosis for patients with unexplained hypokalemia and weakness, even in the absence of clinical features of hyperthyroidism.