Thyrotoxic Periodic Paralysis in Long Standing Graves' Disease: An Unusual Presentation with Normokalemia

CONTEXT: Thyrotoxic periodic paralysis (TPP) is a potentially life-threatening complication of hyperthyroidism that is underdiagnosed and frequently missed. It is relatively common in Asian men with Graves' disease. TPP attacks are frequently associated with hypokalemia. CASE REPORT: Here we report a non-Asian female patient with Graves' disease, who presented with flaccid paralysis associated with an episode of subacute thyroiditis (SAT). Interestingly, she was found to have low normal potassium levels in the serum during the initial attack despite which she continues to require low dose potassium supplementation to prevent recurrent TPP attacks. Unique features in our patient include her gender, ethnicity, time lag between initial diagnosis of Graves' disease, and the development of TPP and borderline low potassium levels, with the continuous need for prophylactic potassium supplementation. CONCLUSION: It is important to be aware of this complication of hyperthyroidism that has a dramatic yet variable presentation, but is readily amenable to therapy.