Hyperthyroidism is the condition that results when the thyroid gland produces excess thyroid hormones. These hormones are responsible for maintaining metabolism and the way the body uses energy. It is also referred to as an overactive thyroid.
Definition & Facts
Located in the front of the neck the thyroid gland produces hormones which help the body to stay warm and controls metabolism. Hyperthyroidism is the condition in which the thyroid produces too much thyroid hormone, and the thyroid is considered overactive.
Women are more likely than men to develop hyperthyroidism. It affects all ages and races. Hyperthyroidism is the opposite of hypothyroidism in which the thyroid does not produce enough hormones for the body to use.
Symptoms & Complaints
- Weight loss
- Hand tremors
- Increased heartbeat
- Sleep problems
- Fatigue and muscle weakness
- Sensitivity to heat
- Decreased menstruation or irregular menstruation
- Frequent bowel movements (although diarrhea is uncommon)
- Brittle and fine hair
In some, swelling may occur in the front of the neck where the thyroid is located. This is due to the enlargement of the thyroid gland and is called a goiter. Symptoms may be mistaken for stress in younger patients.
Most cases of hyperthyroidism are classified as Graves' disease. Graves' disease is an autoimmune disorder which causes antibodies from the immune system to mistakenly attack the thyroid into producing too much thyroid hormone.
Hyperthyroidism resulting from Graves' disease include symptoms of Graves' ophthalmopathy (where the muscles behind the eyes swell and push them forward out of their normal orbits) and Graves' dermopathy (red or swollen skin on the shins and feet).
Hyperthyroidism is also caused by hyper-functioning thyroid nodules in a condition known as toxic multinodular goiter. In this case one or more nodes of the thyroid gland grow and increase their production of thyroxine beyond normal limits. This may also be referred to as Plummer's disease.
Diagnosis & Tests
There are several tests that can be done to check for hyperthyroidism. During a physical examination, a physician will go over medical history. They will then check for any physical signs such as trembling hands, overactive reflexes, or warm and moist skin. They will also feel the lower front portion of the neck to feel if the thyroid gland is swollen, bumpy or tender. Blood pressure will also be analyzed, and if it is high, it can indicate an overactive thyroid.
After a general physical examination, blood tests will be ordered to check the amount of thyroid hormone present in blood. Once a diagnosis of hyperthyroidism is confirmed tests will be done to determine why the thyroid is overacting. A radioactive iodine uptake tests involves taking a small dose of radioactive iodine. After two, six or 24 hours the levels of iodine store in the thyroid are checked to determine how much has been taken in by the thyroid.
A thyroid scan involves injecting a small radioactive isotope into a vein while images of the thyroid are captured by a camera. Sometimes these two tests can be combined in which case the radioactive iodine can be used to image the thyroid.
Treatment & Therapy
There are several treatment options available for hyperthyroidism. Determining the treatment for the best success depends on the cause of overactive thyroid, age, physical condition and severity of the condition.
- Radioactive iodine- Treatment with radioactive iodine has been used for decades and is considered safe. Since the thyroid uses iodine to produce hormones it will take in any iodine present in blood. In this case the radioactive iodine is absorbed and the levels of thyroxine return to normal. Radioactive iodine is used to induce hypothyroidism in severe cases which is easily treated with thyroid supplements taken every day.
- Beta blockers- These drugs are commonly used to treat high blood pressure. In the case of hyperthyroidism they are used to control blood pressure until thyroid levels return to normal. They are not used to treat the condition but the symptom.
- Anti-thyroid medications- These drugs are used to block the thyroid from producing excess hormones. The most common prescriptions are methimazole and propylthiouracil. Methimazole is the preferred anti-thyroid medication as propylthiouracil can cause liver damage.
- Surgery- This is considered a last resort treatment. Most of the thyroid gland is removed in a thyroidectomy. Afterwards lifelong treatment involving thyroid supplements is necessary.
Prevention & Prophylaxis