Racing Heart Under Stormy Skies: A Journey From Agranulocytosis to Thyroid Storm.

Thyroid storm is a rare, severe, and life-threatening exacerbation of thyrotoxicosis, characterized by dysfunction of the thermoregulatory, central nervous, gastrointestinal, hepatic, and cardiovascular systems. We present a 31-year-old female with newly diagnosed Graves' disease complicated by carbimazole-induced agranulocytosis. The delay in initiating adjunctive therapy to control the thyrotoxicosis due to suspected sepsis was followed by rapid development of thyroid storm requiring therapeutic plasma exchange (TPE) and urgent thyroidectomy. This case highlights the importance of prompt recognition and of distinguishing thyroid storm from sepsis in the setting of anti-thyroid drug-induced agranulocytosis and underscores TPE as an effective, well-tolerated bridging therapy for thyroid storm before definitive treatment.