Long-Term Antithyroid Treatment for Hyperthyroidism

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Hyperthyroidism—and autoimmune Graves’ disease that causes hyperthyroidism—is typically treated in three ways: antithyroid drugs, radioactive iodine ablation (RAI), and surgery. In the United States, the first-line treatment has been RAI for the most part. Recently, however, there has been renewed interest in the use of antithyroid drugs, including long-term use of the drugs to restore the thyroid to normal levels.

Antithyroid Drugs

Two antithyroid drugs are used in the United States. The primary drug is methimazole, sometimes abbreviated MMI. The only brand name of methimazole in the United States is Tapazole.

The less commonly-prescribed antithyroid drug is propylthiouracil, which is usually abbreviated as PTU. There are no brand names of PTU and only generic PTU is prescribed. PTU has higher risks of liver toxicity, and as such, is mainly prescribed only when methimazole can’t be tolerated. (PTU is, however, prescribed during the first trimester of pregnancy, when it has minimal risk of causing birth defects when compared to methimazole.)

In the United States, antithyroid drugs have typically been used as a shorter-term treatment of no more than a year to 18 months. After that point, many doctors recommend you receive treatment, usually RAI, that permanently resolves your hyperthyroidism. Surgery is typically reserved for patients who don’t respond to RAI, and for pregnant women whose hyperthyroidism doesn’t respond to—or can’t be treated with—antithyroid drugs.

(Pregnant women can’t receive RAI treatment for their hyperthyroidism because it poses a risk to the developing baby’s thyroid gland.)

Longer-term use of antithyroid drugs has not been recommended, primarily because of a risk of relapse of the hyperthyroidism, as well as concerns about the side effects of antithyroid medications.

In addition to a slight risk of liver damage, antithyroid medications also pose a risk of agranulocytosis, a condition that results in a severe decrease in the production of white blood cells. Agranulocytosis is rare, but can be life-threatening.

Now, a major research study published in 2017 in the journal Thyroid has shown that long-term antithyroid drug therapy should be considered a key treatment option for hyperthyroidism.

The Latest Research on Long-Term Antithyroid Drug Treatment

The researchers reported on the following key results in their Thyroid journal article:

  • Long-term antithyroid drug treatment resulted in an overall remission rate of 57 percent. You are considered in remission if you have a normal thyroid stimulating hormone (TSH) level, normal free T4, and normal total T3 for a year after you stop antithyroid drug treatment.
  • The remission rate was higher in adults (61 percent) compared to those under 21 (53 percent).
  • The rate of overall complications for long-term antithyroid drug treatment was 19.1 percent.
  • Only 1.5 percent of the complications were major complications.
  • The annual remission rate for each year of treatment was 16 percent.
  • The annual remission rate was higher in adults (19 percent) versus non-adults (14 percent).

    A Word from Verywell

    This new research means that more physicians may be willing to consider long-term antithyroid drug treatment for hyperthyroidism. Long-term antithyroid drug treatment has some benefits for you to consider:

    • You have a chance for a remission of your hyperthyroidism and/or Graves’ disease, avoiding permanent hypothyroidism.
    • Your antithyroid drug treatment is reversible, and does not result in irreversibly ablating or removing your thyroid gland. In contrast, RAI and surgery often result in permanent, lifelong hypothyroidism, and you will need to take a thyroid hormone replacement medication for life.
    • You can avoid the risks and expenses associated with surgery.

    The downside of antithyroid drugs include the following:

    • You have a risk of some minor side effects including itching, rashes, hives, joint pain, joint swelling, fever, changes in taste, and nausea. You have a small risk of more serious side effects like liver damage or agranulocytosis.
    • You have a risk of relapse that is greater than the risk associated with RAI. The researchers estimate that up to 70 percent of patients will relapse after the antithyroid drug treatment is stopped.
    • Your remission rate is somewhat lower if you have a large goiter, larger than 80 grams in volume.
    • If you are a cigarette smoker, you are likely to have a lower remission rate on antithyroid drugs.

    Ultimately, it’s worth exploring with your healthcare provider whether or not long-term antithyroid drug treatment is an option for you. This gives you a chance at remission, and if your remission fails, you can still pursue treatment with RAI or surgery if needed.

    Sources:

    Azizi, F. and Malboosbaf, R. "Long-term antithyroid drug treatment: a systematic review and meta-analysis." Thyroid. July 2017, Online http://online.liebertpub.com/doi/pdfplus/10.1089/thy.2016.0652

    Bahn, R. "Hyperthyroidism: Management Guidelines of the American Thyroid Association and the American Association of Clinical Endocrinologists. Endocrine Practice. 2011. Online. https://www.aace.com/files/hyper-guidelines-2011.pdf

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