Medical Care
The optimal therapy for treatment of toxic nodular goiter (TNG) remains controversial. Unlike Graves disease, TNG is not an autoimmune disease and rarely, if ever, remits. Therefore, patients who have autonomously functioning nodules should be treated definitely with radioactive iodine or surgery. Patients with subclinical hyperthyroidism should be monitored closely for overt disease. Some suggest that elderly patients, women with osteopenia, and patients with risk factors for atrial fibrillation should be treated, even those who have subclinical disease.
Sodium iodide I 131 treatment: In the United States and Europe, radioactive iodine is considered the treatment of choice for TNG. Except for pregnancy, there are no absolute contraindications to radioiodine therapy.
Much debate exists regarding optimal dosing of radioactive iodine. Patients with TNG tend to have less uptake than patients with Graves disease; therefore, they are generally considered to need higher doses of sodium iodide I 131. However, recent studies by Allahabadia et al suggest that fixed doses of radioiodine do not demonstrate any difference in response in these two groups of patients (using a fixed dose of 370 megabequerels).
A single dose of radioiodine therapy has a success rate of 85-100% in patients with TNG. Radioiodine therapy may reduce the size of the goiter by up to 40%.
Failure of initial treatment with radioactive iodine has been associated with increased goiter size and higher T3 and free T4 levels, which suggests that these factors may present a need for higher doses of sodium iodide I 131.
In patients with uptakes of less than 20%, pretreatment with lithium, propylthiouracil, or recombinant TSH can increase the effectiveness of iodine uptake and treatment. This treatment may be valuable in elderly patients in whom surgery is considered high risk.
Complications
Hypothyroidism occurs in 10-20% of patients; this is similar to the incidence rate after surgery and is substantially less than in the treatment of Graves disease.
Tracheal compression due to thyroid swelling after radiation therapy is no longer thought to be a risk.
Elderly patients may have exacerbation of congestive heart failure and atrial fibrillation. Pretreat elderly patients with antithyroid drugs.
Thyroid storm is a rare complication, particularly in patients with rapidly enlarging goiters or high total T3 levels. Patients with these conditions should receive pretreatment with antithyroid drugs.
Pharmacotherapy: Antithyroid drugs and beta-blockers are used for short courses in the treatment of TNG; they are important in rendering patients euthyroid in preparation for radioiodine or surgery and treating hyperthyroidism while awaiting full clinical response to radioiodine. Patients with subclinical disease at high risk of complications (eg, atrial fibrillation, osteopenia) may be given a trial of low dose methimazole (5-15 mg/d) or beta-blockers and monitored for a change in symptoms or for progression of disease that requires definitive treatment.
Thioamides: The role of therapy with thioamides (eg, propylthiouracil, methimazole) is to achieve euthyroidism prior to definitive treatment with either surgery or radioiodine therapy. Data suggest that pretreated patients have decreased response to radioiodine. The general recommendation is to stop antithyroid agents at least 4 days prior to radioiodine therapy to maximize the radioiodine effect.
Antithyroid drugs are often administered for 2-8 weeks before radioiodine therapy to avoid the risk of precipitating thyroid storm. Although many physicians no longer consider this treatment necessary, general consensus is that elderly patients or patients with high risk of cardiac complications should receive this treatment.
Both antithyroid drugs and beta-blockers have side effectsβmost commonly pruritic rash, fever, gastrointestinal upset, and arthralgias. More serious potential side effects include agranulocytosis, drug-induced lupus and other forms of vasculitis, and liver damage.
Beta-adrenergic receptor antagonists: These drugs remain useful in the treatment of symptoms of thyrotoxicosis; they may be used alone in patients with mild thyrotoxicosis or in conjunction with thioamides for treatment of more severe disease.
Propranolol, a nonselective beta-blocker, may help lower the heart rate, control tremor, reduce excessive sweating, and alleviate anxiety. Propranolol is also known to reduce the conversion of T4 to T3.
In patients with underlying asthma, beta-1 selective antagonists, such as atenolol or metoprolol, would be safer options.
In patients with contraindications to beta-blockers (eg, moderate-to-severe asthma), calcium channel antagonists (eg, diltiazem) may be used to help control the heart rate.
Surgical Care
Surgical therapy is usually reserved for young individuals, patients with a large nodule or nodules or obstructive symptoms, patients with dominant nonfunctioning or suspicious nodules, patients who are pregnant, patients in whom radioiodine therapy has failed, or patients who require a rapid resolution of the thyrotoxic state.
Subtotal thyroidectomy results in rapid cure of hyperthyroidism in 90% of patients and allows for rapid relief of compressive symptoms.
Restoring euthyroidism prior to surgery is preferable.
Complications of surgery include the following:
Frequency of hypothyroidism is similar to that of those treated with radioiodine (15-25%).
Complications include permanent vocal cord paralysis (2.3%), permanent hypoparathyroidism (0.5%), temporary hypoparathyroidism (2.5%), and significant postoperative bleeding (1.4%).
Other postoperative complications include tracheostomy, wound infection, wound hematoma, myocardial infarction, atrial fibrillation, and stroke.
The mortality rate is almost zero.
Consultations
Consult an endocrinologist for hyperthyroidism that has not responded to medical therapy or if other comorbid conditions are complicating the patient's condition. Refer patients with amiodarone-associated hyperthyroidism to an endocrinologist. In a multinodular goiter with cold and hot areas on thyroid scan findings, fine-needle aspiration may be required to determine the histologic nature of the cold lesions.
Consult an endocrine surgeon if medical therapy fails to maintain the euthyroid state, if compromise of the trachea is noted on imaging studies, or if the patient requests surgical removal.
Consult a thoracic surgeon in the case of a toxic substernal goiter, for which the surgeon may be helpful in further diagnostic and therapeutic measures.
Activity
Activity should be restricted to maintain a heart rate less than 90 beats per minute