A NOT SO SIMPLE THYROID CAUSE OF ST DEPRESSION: THYROTOXIC HYPOKALEMIC PERIODIC PARALYSIS

Abstract

SESSION TITLE: Medical Student/Resident Cardiovascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Thyrotoxic hypokalemic periodic paralysis (THPP) is a rare and reversible endocrine emergency. The excess of thyroid hormone increases the sensitivity of the Na-K-ATPase channels, shifting potassium from the extracellular to the intracellular space. CASE PRESENTATION: A previously healthy 53 year-old man presented with one day of generalized weakness. Associated symptoms included lower extremities paresthesias, headaches, nausea and vomiting in addition to 5 months of fatigue, weight loss and tremors. Physical findings were significant for a heart rate of 117bpm and a blood pressure of 140/65mmHg. Extremities were warm, clammy and well perfused. A fine hand tremor, diffuse weakness and hypotonia were present. EKG showed sinus tachycardia, diffuse ST depression and QT interval prolongation (figure 01). Laboratory showed a critical hypokalemia (at 1.63mEq/L), a suppressed TSH (<0.005µIU/mL) and an elevated T4L (4,03ng/dL). Intravenous potassium chloride was administered. EKG after KCl infusion (Figure 02) showed resolution of the repolarization changes. His muscular weakness also resolved. Patient was discharged with propranolol and methimazole for outpatient follow up. DISCUSSION: THPP is more common in men in between the age of twenty to forty Hypokalemia results in slowed conduction, delayed ventricular repolarization, shortened refractory period and increased automaticity. ECG changes include flattening and inversion of T waves in mild hypokalemia, Q-T interval prolongation and mild ST depression in more severe hypokalemia. Severe hypokalemia can cause torsades de pointes and ventricular tachycardia. Importantly ST depression as in our case is not common and should raise the concern for ischemia if not resolved with potassium reposition. CONCLUSIONS: THPP is a rare cause of hypokalemia which can cause malignant arrythmias. Severe hypokalemia is an unusual cause of ST segment depression, ventricular tachycardia and QT prolongation, being an important differential for ischemic heart disease. Reference #1: Lin YC, Wu CW, Chen HC, Chen HY, Lu IC, Tsai CJ, Kuo WR, Chiang FY. Surgical treatment for thyrotoxic hypokalemic periodic paralysis: case report. World jorunal of surgical oncology. 2012;10(1):21. Reference #2: Osadchii OE. Mechanisms of hypokalemia-induced ventricular arrhythmogenicity. Fundam Clin Pharmacol. 2010; 24:547–59. DISCLOSURES: No relevant relationships by RAIMUNDO BARROS, source=Web Response no disclosure on file for Lucia Belem; No relevant relationships by Ingrid Freitas, source=Web Response No relevant relationships by Simran Kenth, source=Web Response No relevant relationships by Neiberg de Alcantara Lima, source=Web Response No relevant relationships by Danielli Lino, source=Web Response No relevant relationships by José Silva, source=Web Response