The thyroid is a small gland that is located in the throat. It makes hormones that regulate the body's base metabolism by controlling how much energy cells use on a regular basis. Hypersecretion of hormones from the thyroid gland, which is also known as hyperthyroidism, can affect the entire body and be caused by multiple conditions.
The most common cause of hyperthyroidism is Graves disease, the Hormone Foundation notes. This disease is caused by antibodies, formed by the immune system, inadvertently attacking the thyroid gland, which causes the hypersecretion of thyroid hormones. Thyroid nodules, which can be cancerous or benign can also lead to hyperthyroidism. There are also several types of diseases in the category of thyroiditis, which describes any condition that causes inflammation of the thyroid. The inflammation stimulates the thyroid gland to produce additional thyroid hormone.
There are a number of different symptoms that hyperthyroidism can cause, the Mayo Clinic explains. Among them are anxiety or irritability, as well as trouble sleeping. Patients may also suffer from fine muscle tremors, intolerance to heat and perspiration. Other symptoms include a rapid or irregular heartbeat, brittle hair, weight loss despite normal food intake and an increase in the number of bowel movements experienced each day. Graves disease can also cause the development of a goiter and a characteristic bulging of the eyes, which is also known Graves ophthalmopathy. This condition can cause the eyes to tear, become irritated and inflamed and can lead to a widening of the space between the eyes as well as swelling of the lids and increased light sensitivity. In extreme cases, patients may develop double vision, corneal ulcers, and blurred or reduced vision.
If left untreated, hyperthyroidism can cause heart problems due to overstimulation of the heart, leading to atrial flutter or congestive heart failure, Family Doctor explains. Excess thyroid hormone can also make it difficult for the body to use calcium for the purpose of building bone material, leading to osteoporosis and easy fracturing. Patients can also develop red and swollen skin on the feet and shins. Finally, hyperthyroidism can cause a condition known as thyrotoxic crisis, which leads to a sudden worsening of the symptoms of hyperthyroidism. Thyrotoxic crisis is a medical emergency and requires immediate medical care.
Doctors may suspect hyperthyroidism based on a physical exam, which may reveal many of the symptoms of an overactive thyroid. Blood tests can also be done that measure the amount of hormones, known as T3 and T4, which the thyroid is secreting. A thyroid scan can determine if the entire thyroid is affected, or if the hypersecretion is limited to just one portion of the gland. A radioactive iodine uptake test uses specially labeled iodine to determine how much iodine the gland is using. Low intake of iodine indicated thyroiditis, whereas high uptake of the labeled iodine suggests Graves disease or a thyroid nodule.
There are several ways in which hyperthyroidism can be treated. Radioactive iodine can be given to kill off any nodules, which are producing too much thyroid hormone. Medications can also be given, which will inhibit the thyroid's ability to make hormones. In some cases, the thyroid may be surgically removed, which will require the patient then to take synthetic thyroid hormone to compensate for the lost thyroid hormones. Finally, beta-blockers can be given to ease the strain of hyperthyroidism on the heart.