Patients with thyroid dysfunction may be described as euthyroid, hypothyroid, or hyperthyroid to reflect normal, inadequate, and excessive hormone secretion, respectively. Purified or synthetic thyroid preparations are available for the treatment of hypothyroidism (Table 11).17 The amount of daily thyroid hormone given to restore the euthyroid state varies, but for adults it usually lies between 0.05 to 0.15 mg (50 to 150 micrograms) of levothyroxine or its equivalent.
Antithyroid drugs (e.g., methimazole, propylthiouracil) may be used for 12 to 18 months as primary treatment for hyperthyroidism or as preparative therapy before ablative radioiodine therapy and/or surgery. Common complication of antithyroid drugs and a predictable sequela of radioiodine therapy or surgery is hypothyroidism requiring daily thyroid replacement. Key recommendations for practice are presented in Tables 12 and 13.30-32