Acute Muscle Weakness in Graves' Disease: A Case Report of Hypokalemic Thyrotoxic Periodic Paralysis

Abstract

Thyrotoxic periodic paralysis (TPP) is a rare but significant complication of hyperthyroidism, characterized by episodes of muscle weakness or paralysis and associated hypokalemia. This case report details a 30-year-old Latin American male with a history of Graves' disease, presenting with acute muscle weakness and hypokalemia. The patient reported transient episodes of weakness over recent weeks, culminating in a severe episode prompting emergency evaluation. Physical examination revealed marked weakness, particularly in the lower limbs, a moderate goiter, and bilateral exophthalmos. Laboratory workup confirmed hypokalemia and uncontrolled thyrotoxicosis, with an elevated Burch-Wartofsky Point Scale score suggestive of thyroid storm. Treatment involved potassium and magnesium replacement, along with re-initiation of methimazole and propranolol, leading to significant improvement within hours. Persistent thyrotoxicosis was attributed to inconsistent medication adherence, prompting counseling on adherence strategies and discussion of more definitive treatment options. This case highlights the importance of recognizing TPP across diverse populations, emphasizes prompt management of hypokalemia and thyrotoxicosis to prevent severe complications, and underscores the critical role of patient education in chronic disease management. By contributing to the growing body of literature on TPP in non-Asian patients, this report supports the need for heightened clinical awareness of TPP in hyperthyroid patients presenting with acute muscle weakness and hypokalemia. Additionally, it emphasizes the importance of a thorough evaluation, prompt management, and patient education to prevent recurrence and achieve long-term management of Graves' disease.

Keywords: acute muscle weakness; electrocardiogram abnormalities; goiter; graves' disease; hypokalemic thyrotoxic periodic paralysis (htpp); medication adherence; non-asian population; potassium imbalance; thyroid storm; thyrotoxicosis.

Figure 1. Moderate-sized, diffusely distributed goiter was felt on palpation of the neck without any discernable nodules.

Figure 2. Bilateral exophthalmos with eyes protruding beyond the orbits.

Figure 3. Initial ECG showing T wave inversion, ST depression, and a prominent U wave consistent with hypokalemia.

Figure 4. Repeat ECG six hours after arrival showing significant signs of improvement with resolution of his T wave inversions, ST depressions and prominent U wave patterns.