Hyperthyroidism is an imbalance of metabolism caused by overproduction of thyroid hormone.
Alternative Names: Thyrotoxicosis; Overactive thyroid
Causes, incidence, and risk factors:
The thyroid gland is located in the neck. It produces several hormones which control the way that every cell in the body uses energy (metabolism). The thyroid is part of the endocrine system.
Hyperthyroidism or thyrotoxicosis occurs when the thyroid releases too many of its hormones over a short (acute) or long (chronic) period of time. Many diseases and conditions can cause this problem, including:
Graves' disease accounts for 85% of all cases of hyperthyroidism.
Additional symptoms that may be associated with this disease:
Signs and tests:
Vital signs (temperature, pulse, rate of breathing, blood pressure) show increased heart rate. Systolic blood pressure may be elevated. Physical examination may reveal thyroid enlargement or goiter.
Laboratory tests that evaluate thyroid function:
This disease may also alter the results of the following tests:
Treatment varies depending on the cause of the condition and the severity of symptoms. Hyperthyroidism is usually treated with antithyroid medications, radioactive iodine (which destroys the thyroid and thus stops the excess production of hormones), or surgery to remove the thyroid.
If the thyroid must be removed with radiation or surgery, replacement thyroid hormones must be taken for the rest of the person's life.
Beta-blockers like propranolol are used to treat some of the symptoms including rapid heart rate, sweating, and anxiety until the hyperthyroidism can be controlled.
Hyperthyroidism caused by Graves' disease is usually progressive and has many associated complications, some of which are severe and affect quality of life.
These include complications caused by use of radioactive iodine, surgery, and medications to replace thyroid hormones. However, hyperthyroidism is generally treatable and rarely fatal.
Calling your health care provider:
Call your health care provider if you have symptoms which could be caused by excessive thyroid hormone production. If the symptoms are associated with a rapid, irregular heartbeat, dizziness, or change in consciousness, go to the emergency room or call the local emergency number (such as 911).
Call your health care provider if treatment for hyperthroidism induces symptoms of under-active thyroid, including mental and physical sluggishness, weight gain, and depression.
There are no general prevention measures to prevent hyperthyroidism.