SUN-514 Thyrotoxic Periodic Paralysis in Adolescence Patient a Case Report and Literature Review

BACKGROUND: Thyrotoxic periodic paralysis (TPP) is an uncommon disorder characterized by acute flaccid paralysis due to hypokalemia. It is diagnosed primarily in Asian adult males and is rare in children and adolescents. Here we report an adolescent male patient of Vietnamese descent who presented to the emergency department with an episode of syncope, muscle weakness, and shortness of breath one day after the initiation of methimazole treatment for Graves’ disease. The laboratory revealed significant hypokalemia. In this report we also included and summarized the reported cases of TPP in adolescent patients since 1997. Clinical Case: A 17-year-old Vietnamese American male who was recently diagnosed with Graves’ disease presented to the emergency department after an episode of syncope, muscle weakness, and difficulty breathing. Two months previously, he began having episodes of tachycardia. He was diagnosed with hyperthyroidism with a TSH of 0.007 mIU/mL and free T 4 > 7 ng/dL (0.8-1.9). He was subsequently evaluated by Cardiology and started on atenolol. He was then seen by Endocrinology 5 days after and started on methimazole 15 mg twice daily. On the next morning after starting methimazole, he reported feeling weak and passed out. His father had found him on the floor, weak and unable to move, approximately 30 minutes after his father “heard a thud upstairs”. The patient recalled that his legs gave out and he “hitting his face on a table”. In the emergency department, he was tachycardic at 116 bpm, widened pulse blood pressure of 131/50 mmHg with normal respiratory rate 24 BR/min. He had diffused and significant muscle weakness on his all extremities including grip strength. His potassium was 1.6 mmol/L (3.5 - 5.2) and magnesium 1.6 mmol/L (1.6-2.3). The rest of his chemistry panel was unremarkable. He had EKG changes consistent with hypokalemia with U waves, also revealing atrial rhythm with first degree AV block, intraventricular conduction delay, and QTc prolongation at 588 (<450). His chest x-ray was normal. Normal saline was administered, and potassium replacement was given with 40 mEq of KCl followed by D5 NS with 40 meq/L KCl at maintenance. He continued taking atenolol and methimazole. He was also given an IV dose of magnesium. His muscle strength returned completely and potassium level returned to normal range at 4.6 mmol/L after 24 hours of treatment. Conclusion: TPP is a rare cause of acute paralysis and can lead to cardiac arrhythmia and death without accurate diagnosis and prompt treatment. Our case should raise awareness of this disorder among pediatricians, emergency department physicians and endocrinologists. Acute paralysis with hypokalemia should also prompt the physician to consider evaluating thyroid function as a differential diagnosis in young Asian men.