A CASE OF THYROTOXIC PERIODIC PARALYSIS IN AN AFRICAN AMERICAN MALE REQUIRING MECHANICAL VENTILATION AND HEMODIALYSIS

Abstract

SESSION TITLE: Medical Student/Resident Critical Care SESSION TYPE: Med Student/Res Case Report PRESENTED ON: October 18-21, 2020 INTRODUCTION: Thyrotoxic periodic paralysis (TPP) represents a rare, acquired form of hypokalemic periodic paralysis characterized by acute onset muscle weakness and hypokalemia. We report a severe presentation requiring mechanical ventilation and hemodialysis (HD). CASE PRESENTATION: A 25 year old African American male presented with bilateral lower extremity weakness and hypokalemia at 1.6 mmol/L with characteristic hypokalemic ECG changes. After receiving 40 mEq IV potassium chloride, his hypokalemia worsened to 1.1. Given acute progression of ascending paralysis to complete paraplegia, 3/5 strength in upper extremities and concern for impending diaphragmatic weakness, he was intubated. Despite an additional 170 mEq of potassium, his repeat K+ was 1.5 with progressive EKG changes. He also had a metabolic acidosis with pH of 7.208 and a lactic acid of 8.7. Given refractory hypokalemia and concern that bicarbonate therapy for acidosis would worsen the hypokalemia, the patient was initiated on HD with a high potassium bath. The team confirmed suspicion of TPP upon return of TSH level <0.015 mU/L and administered 3 doses of 1 mg IV Propranolol during which he exhibited spontaneous extremity movements. Serial labs then revealed a rebound hyperkalemia up to 7.4 mmol/L with characteristic hyperkalemic ECG changes. He received usual stabilizing treatments and a second session of emergent HD to correct the up trending hyperkalemia. Diagnosis and recovery was confirmed after stable potassium levels, resolved acidosis, complete recovery of his neurological exam and notably elevated T4 and T3 levels. He was extubated without complication and discharged home on Propylthiouracil with instructions to follow-up with endocrinology for further evaluation of his hyperthyroidism. DISCUSSION: As compared to prior published cases of TPP most often amongst Asian males, management of this African American patient differed with the use of mechanical ventilation for airway protection due to rapidly progressive ascending paralysis and down trending negative inspiratory forces and vital capacities. It also necessitated the use of hemodialysis to correct both the refractory hypokalemia and concomitant acidosis. It is believed that a thyrotoxic-mediated beta-adrenergic response drives potassium into cells hyperpolarizing muscle fibers, causes an extracellular shift of hydrogen and increases conversion of pyruvate to lactate resulting in acidosis. The concern with addressing this with a bicarbonate drip was that a secondary alkalosis would further intracellularly shift potassium. Fortunately, already having a HD catheter in place allowed for more rapid treatment of the severe rebound hyperkalemia. CONCLUSIONS: Initial suspicion of TPP on the differential for ascending paralysis and earlier use of IV propranolol can prevent progression of paralysis, rebound hyperkalemia, lactic acidosis and life-threatening cardiac arrhythmias. Reference #1: Younis AA. Thyrotoxic Periodic Paralysis as a Presentation of Thyrotoxicosis: A Case Report and review of the literature. Mediterr J Rheumatol. 2018;29(1):46–48. Reference #2: Wong P. Hypokalemic thyrotoxic periodic paralysis: a case series. CJEM. 2003;5(5):353–355. Reference #3: Tassone H, Moulin A, Henderson SO. The pitfalls of potassium replacement in thyrotoxic periodic paralysis: a case report and review of the literature. J Emerg Med. 2004;26(2):157–161. DISCLOSURES: No relevant relationships by Firth Bowden, source=Web Response No relevant relationships by Uday Gulati, source=Web Response No relevant relationships by Asma Qayyum, source=Web Response No relevant relationships by samson zarbiv, source=Admin input