Thyrotoxic Periodic Paralysis (TPP) presents as a triad of acute attacks of muscle weakness, hypokalemia, and thyrotoxicosis. TPP was first described in East Asian countries, specifically Japan and China, where it was found to occur at an overall incidence of 2% and preferentially affected males.1,2 TPP also develops in other ethnicities, however, and given the growing ethnic heterogeneity of global society, it is becoming increasingly important for all physicians to be familiar with the diagnosis and management of TPP. The following case represents a typical presentation of TPP and serves as a valuable resource for informing our differential diagnoses and approach to similar cases in the future.

Case Presentation:

Mr. X is a 52-year old Japanese man with a history of Graves’ Disease that had been treated with methimazole. After several years of euthyroidism, the methimazole was tapered down and discontinued altogether 3 months prior to presentation. One month prior to presentation, Mr. X obtained surveillance thyroid stimulating hormone (TSH) testing, which revealed an exceedingly low level of < 0.02μU/mL. Review of systems revealed increased appetite and oral intake without a change in weight during the preceding 2 weeks, but Mr. X was otherwise asymptomatic, felt well, and had not followed up with his endocrinologist. On the night of presentation, when attempting to climb out of bed, Mr. X noted sudden onset of bilateral painless proximal lower extremity weakness characterized by an inability to walk or even raise his legs.