**Abstract**

Thyroid storm is a rare but life-threatening endocrine emergency. It is an acute exaggerated clinical manifestation of thyrotoxic state. The exact incidence is unknown. It occurs in 1–2% of patients admitted for thyrotoxicosis. It has a mortality of 10–20%. This chapter would help us to understand its clinical manifestations, pathophysiology, and effective treatment. Terminal learning objective would be to diagnose impending storm early and start prompt treatment in day-to-day practice. The chapter would cover pathophysiology including triggers, clinical features including various diagnostic criteria, diagnosis, and treatment of thyroid storm. Indications of surgical treatment in storm will be discussed.

**Keywords:** thyroid storm, endocrine emergency, thyroid crisis, thyrotoxic storm, thyrotoxic crisis
