Muscle paralysis in thyrotoxicosis

Abstract

Thyrotoxic periodic paralysis (TPP) is a condition characterised by muscle paralysis due to hypokalaemia usually secondary to thyrotoxicosis. We report a case of a 31-year-old man with no known comorbidities who presented to a tertiary healthcare unit with a 1-month history of difficulty in breathing, palpitations, weight loss and hoarseness of voice. On examination, his thyroid gland was palpable and fine hand tremors were present. An initial provisional diagnosis of hyperthyroidism was made. Three months after initial presentation, the patient presented in emergency with severe muscle pain and inability to stand. Laboratory results revealed hypokalaemia. All the symptoms reverted over the next few hours on administration of intravenous potassium. A diagnosis of TTP was established. After initial presentation, the patient was treated with carbimazole and propranolol. Once he was euthyroid, radioactive iodine ablation therapy (15 mCi) was carried out as definitive therapy, after which the patient's symptoms resolved; he is currently doing fine on levothyroxine replacement and there has been no recurrence of muscle paralysis.