Thyrotoxic periodic paralysis (TPP) may be difficult to diagnose as it is often mistaken for more familiar causes of hypokalemia and lower extremity paralysis, partially because of the subdued nature of the thyrotoxicosis and due to the unawareness of the disorder. Hypokalemia is often accompanied with TPP which often may lead to the incorrect diagnosis. 

We present a case of a 26 year old male who presented to the emergency department for bilateral lower and upper extremity weakness that started the morning of presentation. The patient had been evaluated at another emergency department several months prior for the same reason. He was treated for hypokalemia but etiology was not elucidated. On presentation laboratory studies revealed a potassium of 1.5 and a TSH of .007. Patient was taken for thyroid uptake scan which revealed increased radioiodine uptake of 83% at 21 hours (normal- 10-36%) which was consistent with Graves Disease. The patient was subsequently treated with potassium, propranolol and was set for radioactive iodine ablation to treat the underlying Graves disease. Patient had resolution of symptoms on discharge.

TPP is often a missed diagnosis in patients with proximal muscle weakness and paralysis. To avoid misdiagnosis, it is important to be aware of this diagnosis and treat the underlying cause.