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Health Information

Diagnosis of Hyperthyroidism

Your doctor will ask about your symptoms, medical history, and family history. A physical exam will be done. Recommended tests may include:

Blood Tests

These tests measure the blood levels of thyroid hormones. This can be done with by checking levels of thyroid stimulating hormone (TSH), free T4, and at times, free T3. The levels of these hormones determine the activity of the thyroid gland. Your blood may also be examined for thyroid antibodies, especially if you are pregnant.

Radioiodine Uptake

This test is used to help define the cause of hyperthyroidism. The thyroid gland uses iodine to make thyroid hormones. For this test, you will orally ingest radioactive iodine. Some of it is taken up by the thyroid gland. The amount of radioactivity is then measured by a radiation counter. In Graves' disease, an autoimmune cause of hyperthyroidism, the amount is elevated. This test is not done on children or pregnant women.

Thyroid Scan

In rare cases, this test may be done at the same time as the radioiodine uptake to evaluate one or more problematic nodules. If suspected on exam, a thyroid ultrasound may also be done. A thyroid nodule may or may not be functioning and is termed hot if it makes too much thyroid hormone, or cold if it does not make any.

Revision Information

  • Hyperthyroidism. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us. Updated March 12, 2013. Accessed November 25, 2013.

  • Hyperthyroidism. The Endocrine Society Hormone Health Network website. Available at: http://www.hormone.org/questions-and-answers/2010/hyperthyroidism. Accessed November 25, 2013.

  • Pearce EN. Diagnosis and management of thyrotoxicosis. Brit Med J. 2006;332:1369-1373.

  • Wu SY, Weiss RE. Radioiodine imaging in the primary care of thyroid disease. Postgrad Med. 2006;119:70-77.