| thyroid hormones | Chemical substances made by the thyroid gland which is located in the front of the neck. The thyroid gland uses iodine to make thyroid hormones. Thyroid hormones are essential for the function of every cell in the body. They help regulate growth and the rate of chemical reactions (metabolism) in the body. The two most important thyroid hormones are thyroxine (t4) and triiodothyronine (T3). (12 Dec 1998) |
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| thyroid ima artery | <anatomy, artery> An inconstant artery; origin, arch of aorta or brachiocephalic artery; distribution, thyroid gland. Synonym: arteria thyroidea ima, lowest thyroid artery, Neubauer's artery. (05 Mar 2000) |
| thyroid imaging | <radiology> Tc-99m pertechnetate 6 mCi, I-123 sodium iodide 200 - 400 uCi PO (12 Dec 1998) |
| thyroid insufficiency | Subnormal secretion of hormones by the thyroid gland. See: hypothyroidism. (05 Mar 2000) |
| thyroid lymph nodes | Nodes of the anterior deep cervical group located around the thyroid gland; they drain into the lateral deep cervical group. Synonym: nodi lymphatici thyroidei. (05 Mar 2000) |
| thyroid nodule | A small circumscribed mass of differentiated tissue associated with the thyroid gland. It can be pathogenic or non-pathogenic. The growth of nodules can lead to a condition of goiter, nodular. most nodules appear between the ages of 30 and 50 years and most are benign. (12 Dec 1998) |
| thyroid receptor antibody | A test that measures the amount of an antibody (thyroid stimulating antibody) which is directed against a receptor for TSH on the thyroid gland. This antibody acts like TSH and stimulates the thyroid to produce excessive amounts of thyroid hormone. The presence of this antibody generally indicates Grave's disease (hyperthyroidism). (27 Sep 1997) |
| thyroid scan | A picture taken of the thyroid gland after radioactive iodine is taken by mouth. (12 Dec 1998) |
| thyroid stimulating antibody | <endocrinology, immunology> Long acting thyroid stimulator is an autoantibody found in many cases of primary thyrotoxicosis which causes hyperplasia of the thyroid by undetermined mechanisms. Human thyroid stimulating immunoglobulin is a different antibody found in all or nearly all cases of primary thyrotoxicosis and may act by binding to the thyrotropin (TSH) receptor site, causing increased synthesis of thyroglobulin. (18 Nov 1997) |
| thyroid stimulating immunoglobulin | <protein> A test that measures the amount of an antibody (thyroid stimulating antibody) which is directed against a receptor for TSH on the thyroid gland. This antibody acts like TSH and stimulates the thyroid to produce excessive amounts of thyroid hormone. The presence of this antibody generally indicates Grave's disease (hyperthyroidism). (27 Sep 1997) |
| thyroid-stimulating immunoglobulins | In Graves' disease, the antibodies to TSH receptors in the thyroid gland. These antibodies are produced by B-lymphocytes and stimulate the receptors, causing hyperthyroidism. Formerly known as LATS (long-acting thyroid stimulator). (05 Mar 2000) |
| thyroid storm | A severe form of hyperthyroidism caused by excessive quantities of thyroid hormones. Thyrotoxicosis may occur as a complication of Grave's disease. Symptoms include weight loss, increased appetite, restlessness, heat intolerance, increased sweating, sleep difficulty, muscle cramps, fatigue, diarrhoea, thirst, muscle atrophy, bounding pulse, tremor, protruding eyes (exophthalmos), high blood pressure and menstrual irregularities. Death can result from congestive heart failure and pulmonary oedema. May be associated with goitre. (27 Sep 1997) |
| thyroid suppression test | A thyroid function test used to diagnose difficult cases of hyperthyroidism, now largely replaced by the thyrotropin-releasing hormone stimulation test; triiodothyronine is administered for a week to 10 days, and a reduction of its uptake by the thyroid gland to less than half of the initial uptake is a normal response. Synonym: Werner's test. (05 Mar 2000) |
| thyroid therapy | The treatment of hypothyroidism. (05 Mar 2000) |
| thyroid toxicosis | Hyperthyroidism resulting from excessive circulating 3,5,3'-triiodothyronine. Synonym: thyroid toxicosis. (05 Mar 2000) |