A 39-year-old Asian male presented to the ED complaining of weakness that began gradually after eating a large meal. His legs were affected more than his arms and, over 3 to 4 hours, the weakness progressed to the point that he could no longer bear weight. He also noted palpitations and tingling in both legs, but there was no headache, dizziness, diplopia, dysphagia, dysarthria or shortness of breath. On further questioning, he reported a tremor, heat intolerance, diaphoresis and palpitations, and a loss of 20 pounds over a 2-month period.