Thyrotoxic Muscle Paralysis as a Rare Cause of Reversible Muscle Weakness: A Case Report

Thyrotoxic periodic paralysis is a clinical condition characterized by muscle weakness in patients with underlying hyperthyroidism. It is usually more commonly seen in patients of Asian origin and has a predisposition for the male population (unlike other thyroid disorders which commonly affect the female population). Findings are more overt in patients who have subclinical hyperthyroidism and there is a risk of them remaining untreated. The symptoms can range from mild muscle weakness to total paralysis. The muscles affected predominantly are the proximal and lower extremities group of muscles. Thyrotoxic muscle paralysis can be precipitated by hyperinsulinemic states such as after heavy meals, physical exertion, obesity, stress, and certain medications like high-dose steroids, antiretrovirals, and interferon therapy. The acute intervention usually revolves around the replenishment of patient's potassium stores followed by maintenance therapy with anti-thyroid medications. We present a case of a Chinese adolescent who presented to us with lower muscle weakness and underlying subclinical hyperthyroidism. It's important for clinicians to be familiar with this disease entity and include it in their differentials whenever a patient with muscle weakness presents. The treatment is simple and can result in rapid improvement of symptoms and should be initiated quickly.