Dictionary

TIA Transient ischemic attack.

thyroxine A hormone that is made by the thyroid gland and is one of the most important thyroid hormones. Four iodine molecules are attached to the molecular structure of thyroxine. Along with the more powerful thyroid hormone triiodothyronine (T3), thyroxine affects almost every process in the body, including body temperature, growth, and heart rate. Also

thyrotropin See thyroid stimulating hormone.

thyrolingual cyst See cyst, thyroglossal.

thyroiditis Inflammation of the thyroid gland. The inflamed thyroid gland can release an excess of thyroid hormones into the bloodstream, resulting in a temporary hyperthyroid state. When the thyroid gland is depleted of thyroid hormones, the patient commonly goes through a hypothyroid (low thyroid) phase. This phase can last for 3 to 6 months, until

thyroidectomy Surgery to remove part or all of the thyroid gland. Thyroidectomy might be done to remove a tumor or to treat hyperthyroidism or goiter (enlarged thyroid gland). Complications of the surgery can include vocal cord paralysis and accidental removal of the parathyroid glands, which are located behind the thyroid gland. Because the parathyroid glands

thyroid-stimulating immunoglobulin A form of immunoglobulin G (IgG) that can bind to thyroid stimulating hormone (TSH) receptors on the thyroid gland. Abbreviated TSI. TSIs mimic the action of TSH, causing excess secretion of thyroxine and triiodothyronine. The TSI level is abnormally high in persons with hyperthyroidism due to Graves disease.

thyroid-stimulating hormone A hormone that is produced by the pituitary gland at the base of the brain in response to signals from the hypothalamus gland in the brain. Abbreviated TSH. TSH promotes the growth of the thyroid gland in the neck and stimulates it to produce more thyroid hormones. When the amount of thyroid hormones

thyroid scan An image taken of a patient’s thyroid gland after the patient swallows radioactive iodine or technetium. The image shows the thyroid gland in action as it accumulates radioactive material. Thyroid scanning is used to determine how active thyroid tissue is in manufacturing thyroid hormone. This can help a physician determine whether inflammation of

thyroid hormone organification defect IIb See Pendred syndrome.

thyroid hormone A chemical substance that is made by the thyroid gland and is essential for the function of every cell in the body. The thyroid gland uses iodine to make thyroid hormones, which help regulate growth and the rate of chemical reactions (metabolism) and are involved in the circadian rhythms that govern sleep, among

thyroid gland See gland, thyroid.