- Drug treatment with antithyroid drugs
- Ablation of the thyroid gland with Radioactive Iodine (RAI)
- Surgery to remove all or part of the thyroid
The focus for those with hyperthyroidism or Graves' disease, therefore, is to normalize thyroid function, if possible, and minimize any symptoms and side effects of the overactive thyroid.
Antithyroid Drug Treatment
Antithyroid drugs have been in use since the 1940s. They are given to help normalize the thyroid levels and eliminate symptoms by making it more difficult for the body to use iodine to produce the thyroid hormone. There are two key antithyroid drugs:Methimazole -- Methimazole (pronounced meth-IM-a-zole), also known by its brand name, Tapazole (pronounced tap-UH-zole) and sometimes called "thiamazole," is used around the world. Carbimazole -- Carbimazole (pronounced car-BIM-a-zole) metabolizes to methimazole and is known by its brand name Neo-Mercazole. It is typically used in the United Kingdom and in some other places in Europe. Methimazole inhibits the thyroid from using iodine to produce the thyroid hormone.
Propylthiouracil -- Propylthiouracil (pronounced proe-pill-thye-oh-YOOR-a-sill) -- is usually abbreviated as PTU. There are no brand names; only the generic PTU is available. PTU has two effects: not only does it inhibit the thyroid from using iodine to produce thyroid hormone, but it also inhibits T4-to-T3 conversion.
PTU has a shorter half life than methimazole and acts more quickly, so some people see the effects of PTU right away. Also, because PTU blocks T4-to-T3 conversion, it may reduce T3 levels quicker, compared with methimazole. PTU, therefore, is sometimes given in thyroid storm or during severe hyperthyroidism because of its fast-acting characteristics.
Antithyroid drugs work best when you can keep a constant amount in your bloodstream. To maintain that constant level, it's important to take your antithyroid drug dose at the proper times, and if you are taking more than one pill a day, evenly space your doses. Generally, methimazole is taken once a day (or twice a day for those on larger doses), and PTU is taken 3 to 4 times per day, or every 6 to 8 hours.
On either drug, restoring normal thyroid levels may require 3 weeks to as long as 3 months to achieve.
Both PTU and methimazole are in the FDA pregnancy category D and considered potentially dangerous to an unborn baby. The risk of hyperthyroidism is, however, greater than the risk of taking a low dose of the medication, and so antithyroid drugs are used in pregnancy. Typically, doctors will recommend the smallest possible dose, and they usually recommend PTU, because methimazole crosses the placental membranes easier.
Breastfeeding on antithyroid drugs is controversial. Some physicians say that it is safe, but prefer PTU over methimazole, since methimazole crosses into breast milk easier.
Some side effects occur in 5 to 10% of patients taking antithyroid drugs, including:
- Mild temporary fever
- Hives, skin rash, itching, allergic reaction
- Abnormal hair loss
- Upset stomach or nausea
- Loss of taste or metallic taste
- Abnormal sensations (tingling, prickling, burning, tightness and pulling)
- Joint and muscle aches
- Drowsiness
- Dizziness
Another risk is agranulocytosis, a condition where the bone marrow suddenly stops making white blood cells, which increases your risk of serious, even life-threatening infection, bleeding, anemia and other significant conditions. Any of the following potential symptoms should be reported immediately to your physician: fever, chills, sore throat, hoarseness, sore mouth, sores in the mouth, coughing, painful urination, shortness of breath, swelling of feet or lower legs, swollen lymph nodes, swollen salivary glands, difficult urination, blood in your urine, unusual bleeding, unusual bruising, red spots on the skin, severe skin rash, nosebleeds, black stools, bloody stools, unusual tiredness, unusual weakness or any feeling of significant discomfort, illness or weakness. Your doctor will test your white blood cell count, and if there are signs of potential agranulocytosis, the doctor will have you stop the antithyroid drug immediately, because you are at risk of a blood infection. Most patients recover from agranulocytosis if the antithyroid drug is stopped and antibiotic therapy is started.
Agranulocytosis is rare, but those most at risk are those at the beginning of treatment, those over 40, those taking PTU and those on a methimazole dose of 40 mg or more. To protect yourself, insist on a baseline white blood count before you start treatment. You may want to push for the doctor to run a white blood count every time your blood is taken to check thyroid function, particularly early on in your treatment.
After you begin antithyroid drugs, your doctor will usually reassess you within four weeks and readjust your dosage accordingly. You'll probably be tested every 2 to 4 months until your thyroid is normalized, and after that point, monitored every 6 months, at minimum.
About.com's Drugs A to Z has complete details about antithyroid drugs:
