[Thyrotoxic hypokalemic paralysis: an infrequent complication and gateway to the diagnosis of hyperthyroidism].

Thyrotoxic hypokalemic paralysis is a rare complication of hyperthyroidism, characterized by acute, reversible episodes of muscle weakness associated with severe hypokalemia, secondary to intracellular potassium redistribution mediated by excess thyroid hormones and activation of the Na+/K+ - ATPase pump. Its incidence is approximately 0.2% and it occurs predominantly in males. In this report, we describe four cases of hypokalemic paralysis associated with thyrotoxicosis. All patients were male, aged between 21 and 37 years. The predominant clinical presentation was acute-onset muscle weakness, mainly proximal, with greater involvement of the lower limbs. In three of the four cases, paralysis was the main initial manifestation of hyperthyroidism due to Graves' disease. Potassium replacement combined with antithyroid therapy and beta-blockers resulted in complete resolution of the muscle weakness and adequate disease control in all patients. Therefore, thyrotoxic hypokalemic paralysis should be considered among the differential diagnoses in patients presenting with muscle weakness, as well as among the complications associated with hyperthyroidism.