Diffuse toxic goiter (Grave’s disease) is the most common cause of hyperthyroidism and results from abnormal stimulation of the thyroid gland by antithyroid antibodies. Other causes of hyperthyroidism include multinodular goiter, excess thyroid hormone, or thyroiditis. Any signs or symptoms suggestive of weight loss, tachycardia, atrial fibrillation, goiter, or proptosis should initiate a more extensive laboratory evaluation of thyroid function. Total thyroxin, free triiodothyronine (T3), free thyroxin (T4), and thyroid-stimulating hormone (TSH) tests are useful in diagnosis. In hyperthyroidism, the free T4 level will be elevated, and the TSH level will be suppressed (154). A new diagnosis of hyperthyroidism necessitates postponement of elective surgery until adequate treatment with antithyroid medication is received because of the risk of thyroid storm. Thyroid storm is associated with mortality of up to 40% (168). Stable thyroid conditions do not require any special preoperative treatments or tests. Ideally, an euthyroid state should be maintained for 3 months before elective surgery. In emergent situations, beta-blockers can be used to counter sympathomimetic drive such as palpitations, diaphoresis, and anxiety. Antithyroid medications such as propylthiouracil (PTU)or radioactive iodine do not render patients euthyroid quickly enough for urgent surgery. Radioactive iodine requires 6 to 18 weeks to establish a euthyroid state (154). When thyroid dysfunction is corrected and maintained for several months, elective surgery can proceed without additional perioperative monitoring. Antithyroid medications should be resumed with return of bowel function. If a prolonged delay in resumption of oral intake is encountered, PTU and methimazole can be administered rectally (169). When time does not permit establishment of a euthyroid state preoperatively, oral administration of PTU and a beta-blocker can be implemented for 2 weeks before surgery, and with careful monitoring, optimal results can be achieved (170). Alternatively, oral beta-blockers, glucocorticoids, and sodium iopanoate can be used for 5 days, followed by surgery on day 6 (169). In the emergent setting, close monitoring of the patient for tachycardia, arrhythmias, and hypertension is necessary. Beta-blockers can control these symptoms until definitive therapy can be initiated after recovery from surgery.
Any signs suggestive of the development of thyroid storm—including hemodynamic instability, tachycardia, arrhythmias, hyperreﬂexia, diarrhea, fever, delirium, or congestive heart failure— mandate transfer to an intensive care setting for optimal monitoring and management in consultation with a medical endocrinologist. Such thyroid instability can be triggered by underlying infection, which requires diagnosis and treatment to facilitate management of this medical emergency. The mortality rate from thyroid storm is reportedly between 10% and 75% (169). Treatment of thyroid storm consists of beta-blockers, thioamides, iodine, iodinated contrast agents, and corticosteroids (151). Aspirin should not be given for fever in the patient with thyroid storm because it may interfere with the protein binding of T4 and T3, resulting in increased free serum concentrations (151).