During the acute phase of thyrotoxicosis, β-adrenoceptor–blocking agents without intrinsic sympathomimetic activity are appropriate in symptomatic patients aged 60 years or more, in those with heart rates greater than 90 beats/min, and in those with cardiovascular disease. Propranolol, 20–40 mg orally every 6 hours, or metoprolol, 25–50 mg orally every 6–8 hours, will control tachycardia, hypertension, and atrial fibrillation. Beta-adrenoceptor–blocking agents are gradually withdrawn as serum thyroxine levels return to normal. Diltiazem, 90–120 mg three or four times daily, can be used to control tachycardia in patients in whom β blockers are contraindicated, eg, those with asthma. Dihydropyridine calcium channel blockers may not be as effective as diltiazem or verapamil. Adequate nutrition and vitamin supplements are essential. Barbiturates accelerate T4 breakdown (by hepatic enzyme induction) and may be helpful both as sedatives and to lower T4 levels. Bile acid sequestrants (eg, cholestyramine) can also rapidly lower T4 levels by increasing the fecal excretion of T4.
These forms of hyperthyroidism occur often in older women with nodular goiters. Free thyroxine is moderately elevated or occasionally normal, but FT3 or T3 is strikingly elevated. Single toxic adenomas can be managed with either surgical excision of the adenoma or with radioiodine therapy. Toxic multinodular goiter is usually associated with a large goiter and is best treated by preparation with methimazole (preferable) or propylthiouracil followed by subtotal thyroidectomy.
During the acute phase of a viral infection of the thyroid gland, there is destruction of thyroid parenchyma with transient release of stored thyroid hormones. A similar state may occur in patients with Hashimoto’s thyroiditis. These episodes of transient thyrotoxicosis have been termed spontaneously resolving hyperthyroidism. Supportive therapy is usually all that is necessary, such as β-adrenoceptor–blocking agents without intrinsic sympathomimetic activity (eg, propranolol) for tachycardia and aspirin or nonsteroidal anti-inflammatory drugs to control local pain and fever. Corticosteroids may be necessary in severe cases to control the inflammation.