Thyroid function must be well
controlled prior to anesthesia to avoid thyrotoxic crisis, which can be
triggered by any form of stress including surgery, but also by iodine-based
contrast agents. Baseline therapy consists of antithyroid drugs, such as
methimazole, carbimazole, and propylthiouracil. However, it is important to
realize that, in order to be effective, either of these drugs must be given
6 to 8 weeks before anesthesia. For more emergent interventions, potassium
iodide and beta-blockers (e.g., propranolol or atenolol) for 7 to 10 days
are effective in controlling the symptoms. A complete blood count with
differentiation should be ordered, especially for patients on antithyroid
drugs, which rarely can cause agranulocytosis, aplastic anemia, liver
problems, and lupus-like syndromes. Cardiac function should be assessed by
appropriate means. Adequate anxiolysis should be provided.