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-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-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.
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…
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…
thyrolingual cyst See cyst, thyroglossal.
thyrotropin See thyroid stimulating hormone.
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…
TIA Transient ischemic attack.
tibia The larger of the two long bones in the lower leg. The tibia is familiarly known as the shinbone.
tibia vara A condition that is characterized by disturbance of normal growth in the inner part of the upper tibia. Tibia vara causes a bowlegged gait and can impair the knees significantly. It is most common in children of African descent. Treatment usually involves surgery, although a knee-ankle-foot orthosis brace may be used. Also known…
tibial bowing Improper growth of the tibia in the leg that causes bowlegs or other leg problems. The tibia may bow anteriorly (in the front) or posteriorly (in the back). See also tibia vara.