Hyperthyroidism (often called overactive thyroid) is a condition in which your thyroid gland produces too much thyroid hormone (thyroxine). The thyroid gland is located at the front of the neck just above where your collarbones meet and makes the hormones that control the way every cell in the body uses energy. This process is called metabolism. Hyperthyroidism can accelerate your body's metabolism significantly, causing sudden weight loss, a rapid or irregular heartbeat, sweating, and nervousness or irritability.
During a physical exam your doctor may look for slight tremor in your fingers when they're extended, overactive reflexes, eye changes and warm, moist skin. Your doctor will also examine your thyroid gland as you swallow to see if it's enlarged, bumpy or tender and check your pulse to see if it's rapid. Diagnosis of hyperthyroidism is made with a blood test to measure levels of the thyroid hormones (T4 and T3).
It is also useful to measure the level of thyroid-stimulating hormone (TSH). This hormone is secreted from the pituitary gland and stimulates the thyroid to produce thyroid hormone. The pituitary constantly monitors our thyroid hormone levels, and if it senses the slightest excess of thyroid hormone in blood, it stops producing TSH. This means a low blood TSH may suggest that the thyroid is overproducing thyroid hormone.
Other special tests may be used to distinguish among the various causes of hyperthyroidism. Because the thyroid gland normally takes up iodine in order to make thyroid hormones, measuring how much radioactive iodine or technetium is captured by the gland can be a very useful way to measure its function. The dose of radiation with these tests is very small and has no side effects. You'll be checked after two, six or 24 hours - and sometimes after all three time periods - to determine how much iodine your thyroid gland has absorbed. Such radioactive thyroid scan and uptake tests are often essential to know what treatment should be used in a patient with hyperthyroidism, and it's especially important if your doctor thinks your hyperthyroidism is caused by Graves' disease.
Thyroid scan. During this test, you'll have a safe radioactive isotope injected and a special camera produces a computerized image of your thyroid gland.
There are different treatments for hyperthyroidism. The kind of treatment you have depends on your age, what is causing your hyperthyroidism, how much thyroid hormone your body is making, and other medical conditions you may have. Each kind of treatment has benefits and risks. For some people, more than one kind of treatment may be needed. Antithyroid medicine and radioactive iodine are the ones doctors use most often. In rare cases, surgery (thyroidectomy) may be recommended. Hyperthyroidism can lead to more serious problems. So even if your symptoms are not bothering you, you still need treatment.
Radioactive iodine is often recommended is often recommended if you have Graves' disease and are older than 50, or if you have thyroid nodules (toxic multinodular goiter) that are releasing too much thyroid hormone. Radioactive iodine is taken by mouth and absorbed by your thyroid gland, where it causes the gland to shrink and symptoms to subside, usually within three to six months. The treatment causes the thyroid gland to be underactive (hypothyroidism), and you may eventually need to take medication every day to replace thyroxine. Used for more than 60 years to treat hyperthyroidism, radioactive iodine has been shown to be generally safe.
Anti-thyroid medications gradually reduce symptoms of hyperthyroidism by preventing your thyroid gland from producing excess amounts of hormones. Symptoms usually begin to improve in six to 12 weeks, but treatment with anti-thyroid medications typically continues at least a year and often longer. For some people, this clears up the problem permanently, but other people may experience a relapse.