Graves' disease medical therapy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Medical Therapy
Medical treatment of Graves' disease includes antithyroid drugs, radioactive iodine and thyroidectomy (surgical excision of the gland).
Treatment of the hyperthyroidism of Graves disease may be with medications such as carbimazole, methimazole or propylthiouracil (PTU), which reduce the production of thyroid hormone, or with radioactive iodine. Surgical removal of the thyroid is another option, but still requires preoperative treatment with methimazole or PTU. This is done to render the patient "euthyroid" (i.e. normothyroid) before the surgery since operating on a frankly hyperthyroid patient is dangerous. Therapy with radioactive iodine (I-131) is the most common treatment in the United States. Thyroid blocking drugs and/or surgical thyroid removal is used more often than radioactive iodine as definitive treatment in Europe, Japan, and most of the rest of the world.
The development of radioactive iodine (I-131) in the early 1940s at the Mallinckrodt General Clinical Research Center and its widespread adoption as treatment for Graves' Disease has led to a progressive reduction in the use of surgical thyroidectomy for this problem. In general, RAI therapy is effective, less expensive, and avoids the small but definite risks of surgery. Treatment with antithyroid medications must be given for six months to two years, in order to be effective. Even then, upon cessation of the drugs, the hyperthyroid state may recur. Side effects of the antithyroid medications include a potentially fatal reduction in the level of white blood cells.
Antithyroid drugs
The main antithyroid drugs are methimazole (US), carbimazole (UK) and propylthiouracil. These drugs block the binding of iodine and coupling of iodotyrosines. The most dangerous side-effect is agranulocytosis (1/250, more in PTU); this is an idiosyncratic reaction which does not stop on cessation of drug. Others include granulocytopenia (dose dependent, which improves on cessation of the drug) and aplastic anemia. Patients on these medications should see a doctor if they develop sore throat or fever. The most common side effects are rash and peripheral neuritis. These drugs also cross the placenta and are secreted in breast milk.
Radioiodine
This modality is suitable for most patients, although some prefer to use it mainly for older patients. Indications for radioiodine are: failed medical therapy or surgery and where medical or surgical therapy are contraindicated.
Contraindications to RAI are pregnancy (absolute), ophthalmopathy (relative- it can aggravate thyroid eye disease), solitary nodules. Disadvantages of this treatment are a high incidence of hypothyroidism (up to 80%) requiring hormone supplementation. It acts slowly and has a relapse rate that depends on the dose administered.