Thyrotoxic periodic paralysis presenting with transient ventricular arrhythmia: a rare variant presentation of Graves' disease.

Thyrotoxic periodic paralysis (TPP) is a rare variant presentation associated with thyrotoxicosis. It is characterised by acute hypokalaemic paralysis due to intracellular potassium shift. We describe a man in his early 30s who presented with sudden-onset flaccid quadriparesis and transient self-reverted broad-complex tachycardia. Arterial blood gas analysis revealed severe hypokalaemia (1.2 mmol/L; reference range 3.5-5.1 mmol/L). Thyroid function tests demonstrated suppressed thyroid-stimulating hormone (<0.01 mIU/L; reference range 0.4-4.0 mIU/L) with markedly elevated free triiodothyronine and thyroxine levels, consistent with thyrotoxicosis due to Graves' disease. He was treated with cautious intravenous potassium replacement and initiation of antithyroid therapy with beta-blockade, resulting in rapid and complete neurological recovery. This case underscores the importance of recognising TPP as a distinct clinical presentation of thyrotoxicosis in young men presenting with acute paralysis and cardiac arrhythmia.