Hyperthyroidism, or overactive thyroid disease, means your thyroid gland makes and releases too much thyroid hormone. The thyroid gland is located in the front of your neck, just below your Adam’s apple. It makes hormones that control your metabolism. Metabolism is the pace of your body’s processes and includes things like your heart rate and how quickly you burn calories.
Hyperthyroidism can affect your metabolism. It can also cause nervousness, increased perspiration (sweatiness), rapid heartbeat, hand tremors, difficulty sleeping and weight loss.
Hyperthyroidism usually begins slowly, so its symptoms can be mistaken for stress or other health problems. It can cause a variety of symptoms, including:
Older adults may have subtle symptoms, such as increased heart rate, increased perspiration and a tendency to become more tired during normal activities.
If your hyperthyroidism is caused by Graves’ disease, you may also have Graves’ opthalmopathy, a disorder that affects your eyes. These symptoms may show up before, after or at the same time as your symptoms of hyperthyroidism. In Graves' opthalmopathy, the muscles behind the eyes swell and push the eyeballs forward. Often, the eyeballs will actually bulge out of their normal position. The front surfaces of the eyeballs become can dry, red and swollen. You may notice excessive tearing or discomfort in your eyes, sensitivity to light, blurry or double vision, and less eye movement.
In more than 70% of cases, hyperthyroidism is caused by an autoimmune disorder called Graves’ disease. Normally, antibodies produced by the immune system help protect the body against viruses, bacteria and other foreign substances. An autoimmune disease is when your immune system produces antibodies that attack your body's tissues and/or organs. With Graves' disease, antibodies produced by the immune system stimulate the thyroid, making it produce too much hormone. Doctors think Graves’ disease may run in families. It is most common among young women.
Two other common causes for hyperthyroidism include:
If you have symptoms of an overactive thyroid, your doctor will check for an enlarged thyroid gland, rapid pulse, moist skin, eye changes and a slight tremor in your fingers or hand. The diagnosis can be confirmed with blood tests that measure the amount of thyroid hormone in your blood.
If your blood tests show an overactive thyroid, your doctor may do a thyroid scan to see if your entire thyroid is affected (which indicates Graves' disease) or if you have hyperfunctioning thyroid nodules or thyroiditis.
Your doctor may also do a radioactive iodine uptake test to measure your thyroid's ability to take up iodine. A high uptake of iodine means your thyroid gland may be producing too much hormone, which indicates Graves’ disease or a hyperfunctioning thyroid nodule. A low uptake of iodine indicates thyroiditis as the cause of your hyperthyroidism.
There are several treatments for hyperthyroidism. Your doctor will choose an appropriate treatment based on your age, your physical condition, the cause of your hyperthyroidism and how severe your condition is.
If it is not treated, hyperthyroidism can lead to other health problems. They include:
Written by familydoctor.org editorial staff