What Is It?
Hyperthyroidism is a condition in which your body makes too much thyroid hormone. It is also called overactive thyroid.
Thyroid hormones are made by the thyroid gland. The thyroid gland is located in the lower front of the neck.
Thyroid hormones regulate the body's energy. When levels of thyroid hormones are unusually high, the body burns energy faster and many vital functions speed up.
Hyperthyroidism is usually caused by the thyroid gland producing too much thyroid hormone. The three most common reasons for this are:
Rarely, the condition is caused by the pituitary gland making too much thyroid-stimulating hormone (TSH). This causes the thyroid gland to produce too much thyroid hormone.
Certain types of thyroid inflammation (thyroiditis) can cause short-term hyperthyroidism. This can occur after childbirth or after viral infections, for example.
In very rare situations, excess thyroid hormone can come from a source outside the thyroid. For example, abnormal tissue growth in the ovary can secrete thyroid hormone.
Symptoms of hyperthyroidism also can be caused by taking excessive amounts of thyroid supplements.
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