Hyperthyroidism is a diagnosis existing along a spectrum of severity. Patients present with a variety of signs and symptoms: tachycardia, elevated heart rate, anxiety, changes in mental status, gastrointestinal disturbances, and hyperthermia. Management of subclinical hyperthyroidism and thyrotoxicosis without thyroid storm is heavily dependent on outpatient evaluation. Thyroid storm is the most severe form of hyperthyroidism with the highest mortality. Management of thyroid storm follows a stepwise approach, with resuscitation and detection of the precipitating cause being paramount. Special attention should be paid to cardiac function in patients with thyroid storm before treatment, as these patients may develop cardiac collapse.