Thyrotoxic Periodic Paralysis and Complicated Thyrotoxicosis, Two Presentations of Hyperthyroidism with Notable Differences in their Clinical Manifestations: An Experience from a Tertiary Care Hospital in the United States

Abstract

Objective: Thyrotoxic periodic paralysis (TPP) is a muscular disorder characterized by sudden episodes of muscle weakness and hypokalemia in the setting of thyrotoxicosis. We aimed to report our experience with TPP in West Texas and compare its clinical presentation to that of patients admitted for complicated thyrotoxicosis.

Methods: Retrospective review of records of adult patients with admission diagnosis of hyperthyroidism, thyrotoxicosis, and/or discharge diagnosis of periodic paralysis seen at our institution in a 6-year period.

Results: Patients admitted for complicated thyrotoxicosis were more commonly females of a mean age of 44 years. Patients with TPP were more commonly Hispanic males of a mean age of 27 years. Despite no significantly different thyroid hormone levels, patients with TPP presented with less-severe signs and symptoms of hyperthyroidism, as reflected by lower Burch-Wartofsky score on admission (19 vs. 35; P<.001) and lower occurrence of atrial fibrillation in the TPP group (0% vs. 36%; P<.001). Finally, 89% of TPP patients presented with corrected QT (QTc) prolongation, whereas only 19% of thyrotoxic patient presented with a prolonged QTc.

Conclusion: Hispanic patients with TTP seems to have relative resistance to the actions of thyroid hormones and commonly present with QTc prolongation, a risk factor for cardiac arrhythmias.

Abbreviations: BWS = Burch-Wartofsky point scale; EKG = electrocardiogram; FT3 = free triiodothyronine; FT4 = free thyroxine; ICD = International Classification of Diseases; QTc = corrected QT; TPP = thyrotoxic periodic paralysis.