Ana Maria Kausel, MD, is a double board-certified endocrinologist affiliated with Mount Sinai St. Luke's/Mount Sinai West in New York City.
Hyperthyroidism is a disease that occurs when your thyroid gland—a small, butterfly-shaped gland located in your neck—produces too much thyroid hormone.
Graves’ disease is the most common cause, affecting over 70% of people with hyperthyroidism. In Graves’ disease, a person’s immune system inappropriately produces antibodies that overstimulate the thyroid gland, causing excessive thyroid hormone production.
Hyperthyroidism can increase metabolism, leading to weight loss, frequent bowel movements, sweating, a fast heart rate, and more. Blood tests diagnose it, and treatment typically involves taking prescription medication or undergoing radioactive iodine ablation. Less commonly, surgical removal of the thyroid gland may be performed.
The main cause of hyperthyroidism in the U.S. is an autoimmune disease called Graves' disease. In this disease, antibodies attack the thyroid gland causing it to enlarge and produce excess thyroid hormone. Other causes of hyperthyroidism include toxic multinodular goiter, thyroiditis, taking supplements that contain high amounts of iodine or animal thyroid tissue, and taking too much thyroid hormone.
Hyperthyroidism is treated with prescription medication, radioactive iodine therapy, or surgery. The treatment chosen depends on factors like the cause behind the hyperthyroidism, the severity of the disease, the presence of thyroid eye disease, and the patient’s age and overall health.
Hyperthyroidism causes your body's metabolism to accelerate. This leads to a variety of symptoms such as tachycardia, weight loss, anxiety and irritability, tremor (especially of the hands), insomnia, sweating, and frequent bowel movements. If hyperthyroidism is uncontrolled or untreated, a heart arrhythmia called atrial fibrillation and bone loss (osteoporosis) may develop.
Unfortunately, the answer is not so straightforward. While radioactive iodine and surgery can permanently cure hyperthyroidism caused by Graves' disease, a person will still need to take lifelong hormone replacement. Likewise, certain types of thyroiditis that may cause a hyperthyroid phase (e.g., postpartum thyroiditis) are not necessarily cured, as they may recur after future pregnancies.
Goiter refers to an abnormal growth or enlargement of the thyroid gland. A goiter can occur for many reasons, including when thyroid function is underactive (hypothyroidism), overactive (hyperthyroidism), or normal (euthyroidism). While some people experience no symptoms with a goiter, others may have a feeling of fullness in their neck, changes in their voice, or have problems breathing or swallowing, among other symptoms.
This inflammatory eye condition, also called thyroid eye disease (TED) or Graves' orbitopathy, occurs in about 30% of people with hyperthyroidism from Graves' disease. Symptoms may include a gritty sensation in the eyes, excessive tearing, light sensitivity, bulging out of the eyes, and double vision.
Thyroid cancer occurs when healthy thyroid cells become abnormal and grow uncontrollably. A person with thyroid cancer may have no symptoms or experience a lump, swelling, or pain in the front of the neck. While there are different types of thyroid cancer (some are more serious than others), for most, the treatment entails surgical removal of part of or the whole gland.
Thyroiditis means “inflammation of the thyroid gland.” There are different types of thyroiditis, depending on the underlying cause behind the inflammation (an autoimmune process or viral infection, for example). Thyroiditis may cause no change in thyroid function, or it may cause the gland to be underactive or overactive.
Thyroxine (T4) is one of two major hormones produced and released into the bloodstream by your thyroid gland. The other major hormone is triiodothyronine (T3). Once in the bloodstream, these hormones enter cells in your body where they perform many functions, including regulating metabolism, body temperature, heart rate, and digestion, to name a few.
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