Thyroid storm is a life-threatening exacerbation of hyperthyroidism that can develop in patients with undiagnosed or untreated hyperthyroidism when stressed. It is characterized by worsening signs and symptoms of thyrotoxicosis including cardiac dysfunction, hyperglycemia, altered mental status, and seizures. Diagnosis is based on clinical features and scoring systems, with a Burch-Wartofsky score of over 45 suggestive of thyroid storm. Treatment involves supportive care, administration of beta blockers, antithyroid medications, iodine, and glucocorticoids to reduce thyroid hormone levels and symptoms.