Thyroid Storm

Clinical features are similar to those of thyrotoxicosis, but more exaggerated. Cardinal features include fever (temperature usually over 38.5°C) and tachycardia out of proportion to the fever. Nausea, vomiting, diarrhea, agitation, and confusion are frequent presentations. Coma and death may ensue in up to 20% of patients. Thyroid function abnormalities are similar to those found in uncomplicated hyperthyroidism. Therefore, thyroid storm is primarily a clinical diagnosis.

Treatment includes supportive measures such as intravenous fluids, antipyretics, cooling blankets, and sedation. Antithyroid drugs are given in large doses. Propylthiouracil is preferred over methimazole because of its additional action of impairing peripheral conversion of thyroxine to triiodothyronine. The recommended initial dose of propylthiouracil is 200 to 300 mg every 6 hours. Propylthiouracil and methimazole can be administered by nasogastric tube or rectally if necessary. Neither of these preparations is available for parenteral administration in the United States.

Iodides, orally or intravenously, are used after the first dose of an antithyroid drug has been administered . The radiographic contrast dyes may be used to block thyroid hormone release (as a result of the iodide released from these agents) and to inhibit thyroxine to triiodothyronine conversion. beta-Adrenergic receptor antagonists, such as propranolol and esmolol, and Ca2+ channel blockers may also be used to control tachyarrhythmias. Dexamethasone (0.5 to 1 mg intravenously every 6 hours) is recommended both as supportive therapy and as an inhibitor of conversion of thyroxine to triiodothyronine. Finally, treatment of the underlying precipitating illness is essential.

Category: Pharmacology Notes