Hyperthyroidism occurs when the thyroid produces excess thyroid hormone. The thyroid gland is located in the neck and produces several hormones, which control metabolism, or the way cells use energy. Hyperthyroidism is a common disorder affecting over two million Americans, most of whom are women.
The most common cause of the condition is Graves' disease, which accounts for 85 percent of cases. Hyperthyroidism also can result from nodular goiter, a condition in which an inflammation of the thyroid occurs due to viral infections or other causes, ingestion of excessive amounts of thyroid hormone, and ingestion of excessive iodine.
Initially, many patients do not experience any symptoms and therefore do not get diagnosed with hyperthyroidism until it is more advanced. In older people, some or all of the typical symptoms of hyperthyroidism may be absent, and the patient may just lose weight or become depressed. Typical symptoms of the condition include:
Your doctor will first perform a physical examination to check for any obvious symptoms of hyperthyroidism. In addition, your doctor may run other tests, including:
Blood Tests: Blood tests are performed that measure the levels of the thyroid hormones, T4and T3, which must be high to make a diagnosis of hyperthyroidism. The level of thyroid stimulating hormone (TSH) also is measured. With hyperthyroidism TSH is low while T4 and T3 levels are high.
Treatment varies depending on the cause of hyperthyroidism and the severity of symptoms. Treatment options include:
Antithyroid Medications: Antithyroid drugs may be prescribed to suppress the production and release of thyroid hormones by inhibiting the use of iodine by the thyroid. Side effects may include skin rash, joint pains, fever, low white count and jaundice.
Radioactive Iodine: This is the preferred treatment of hyperthyroidism caused by Graves' disease. A radioactive iodine tablet is ingested and then taken up by thyroid cells. These overactive cells are damaged so that the thyroid can shrink in size and produce hormones at normal levels. Although this is a safe treatment, most people eventually become hypothyroid after radioactive iodine therapy and therefore require lifelong thyroid hormone replacement therapy. Radioactive iodine therapy cannot be given to pregnant women or those who are breastfeeding.
Reviewed by health care specialists at UCSF Medical Center.