A Trajectory of Thyroid Function: From Thyrotoxic Paralysis to Post-ablative Hypothyroidism.

Acute flaccid paralysis can obscure the underlying endocrine cause in thyrotoxic periodic paralysis (TPP), a rare but potentially life-threatening presentation of Graves' disease. We describe a 23-year-old Cantonese man who presented with sudden bilateral proximal lower limb weakness and severe hypokalaemia after a high-carbohydrate meal. Subsequent investigations revealed thyrotoxicosis consistent with Graves' disease. Management involved prompt potassium replacement, propranolol, and cautious initiation of carbimazole to avoid overtreatment. The patient later underwent radioactive iodine ablation, which successfully resolved thyrotoxicosis but led to post-ablative hypothyroidism requiring levothyroxine. This case underscores that TPP may represent the initial clinical expression of thyroid disease and highlights the critical importance of timely identification, meticulous management, and continued surveillance to mitigate iatrogenic risks.