Since the treatment of hyperthyroidism may last for a few years, a follow-up plan must be established.
Antithyroid Drugs.--Patients treated with ATDs should generally be seen initially at 4- to 12-week intervals, depending on the severity of the illness, until euthyroidism is achieved. At this time, the ATD dose can often be reduced. Patients are then monitored every 3 to 4 months thereafter while continuing to take ATDs. An interval examination should include weight, pulse, blood pressure, thyroid, and an eye examination. Thyroid function tests should include an estimation of free T4, and if clinical symptoms and signs of hyperthyroidism are present, a T3 determination may also be indicated. The serum TSH level may remain suppressed for several months even after T4 and T3 levels normalize, yielding potentially misleading laboratory results.Once ATDs are discontinued, patients should be seen at 4 to 6-week intervals for the first 3 to 4 months after the medication is stopped, and then at increasing intervals for the duration of the first year. If clinical and biochemical euthyroid status persists, patients should be evaluated yearly for the next 2 to 3 years and at increasing intervals thereafter.
Radioactive Iodine.--Patients should be seen at 4- to 6-week intervals for the first 3 months following radioactive iodine therapy, and then at intervals as the clinical situation dictates. Hypothyroidism generally ensues following treatment within the first 6 to 12 months following therapy, but may occur at any time. Therefore, at least annual follow-up is necessary for those individuals who continue to be euthyroid. Levothyroxine sodium should be administered when sustained hypothyroidism develops, the end point of replacement therapy being a normal free T4 estimate and TSH level. Once patients are on a stable dose of levothyroxine, they may be followed at yearly intervals. At subsequent visits, a serum TSH measurement is probably sufficient to assure the adequacy of therapy.
Surgery.--After thyroidectomy, the patient should be followed as warranted for postoperative care, and at approximately 2 months after surgery, to assess thyroid status. Recurrent hyperthyroidism can occur after surgery, but hypothyroidism is far more common, and depends primarily on the size of the thyroid remnant. If levothyroxine therapy is necessary, patients can be followed at yearly intervals after establishing clinical and biochemical euthyroidism. Patients who are euthyroid following surgery should also be followed yearly, using the serum TSH level to document euthyroidism.