The thyroid gland is small, but its influence over the body is powerful. Hormones produced by the thyroid gland are responsible for controlling the body’s rates of metabolism and growth, as well as regulating the levels of calcium in the blood. The thyroid is located at the front of the throat. It is shaped like a butterfly and weighs about an ounce.
Causes
Graves’ disease is the most common form of hyperthyroidism, or overactive thyroid, according to the Merck Manuals. Graves’ disease is an autoimmune disorder, meaning that it occurs when the body mistakenly mounts a defensive immune response against its own healthy tissues. In Graves’ disease, antibodies sent by the immune system attack the thyroid.
Drugs such as amiodarone and lithium sometimes cause hyperthyroidism. Iodine, an essential ingredient in the production of thyroid hormone, can also cause hyperthyroidism when it is consumed in excessive amounts, as sometimes occurs when a patient is taking contrast agents for X-ray studies.
Effects
When the thyroid is overactive, it produces and secretes an excess amount of hormone. Two hormones produced by the thyroid gland, thyroxine and triiodothyronine, wield a powerful influence over the rates at which the body metabolizes energy. An increase in thyroxine, also known as T4, boosts the rate of metabolism to abnormally high levels. This can cause weight loss, anxiety, heat intolerance and heart rate irregularities.
The presence of goiter, a condition in which the thyroid gland is enlarged, can also indicate hyperthyroidism.
Diagnosis
The diagnosis of hyperthyroidism begins when patients report symptoms pointing to the condition to a doctor. A doctor will take a thorough patient history, noting any family history of thyroid disorders. Blood tests will be ordered to detect the levels of thyroid hormone in the blood.
A thyroid scan can also provide useful information in the diagnosis of hyperthyroidism. RadiologyInfo.org explains that a thyroid scan involves the use of radioactive iodine in conjunction with a device called a gamma camera, which takes pictures of the thyroid gland from various angles.
Treatment
The cardiovascular symptoms of hyperthyroidism can be treated with beta-blockers--high blood pressure drugs that reduce heart rate.
Antithyroid drugs such as propylthiouracil can prevent excessive hormone production, according to MayoClinic.com. In other instances, doctors may use radioactive iodine to shrink the thyroid gland. Thyroidectomy, in which part or all of the thyroid gland is removed by surgery, is another treatment option.
Prognosis
In some cases, according to MayoClinic.com, antithyroid drugs can end hyperthyroidism permanently. Often, forms of hyperthyroid treatment such as radioactive iodine or surgery can reduce thyroid hormone production to levels so low that lifelong synthetic hormone replacement therapy is needed.
