Thyroid storm is usually due to inadequate treatment of hyperthyroidism. It is often precipitated by stress, and the disorder may be clinically difficult to differentiate from sepsis or transfusion reactions. Symptoms include fever, delirium, seizures, tachycardia, vomiting, and diarrhea. Although the serum levels of T3 and T4 are elevated in hyperthyroidism, thyroid storm is a clinical diagnosis.