| IR | drop of voltage across a resistor produced by a current; ileal resection; immune response; immunizat... |
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| IRV | inferior radicular vein; inspiratory reserve volume; inverse ratio ventilation |
| ITA | inferior temporal artery; internal thoracic artery; International Tuberculosis Association |
| ITQ | inferior temporal quadrant |
| ITV | inferior temporal vein |
| thyroid scan | A picture taken of the thyroid gland after radioactive iodine is taken by mouth. (12 Dec 1998) |
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| 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 hormone | <endocrinology> Polypeptide hormone (28 kD), secreted by the anterior pituitary gland, that activates cyclic AMP production in thyroid cells leading to production and release of the thyroid hormones (T4 and T3). T4 and T3 blood levels feedback on the pituitary gland and decrease thyroid stimulating hormone production when T3 and T4 levels are high. (27 Sep 1997) |
| thyroid-stimulating hormone | thyroid stimulating hormone |
| thyroid-stimulating hormone-releasing factor | <protein> See thyrotrophic releasing hormone. (18 Nov 1997) |
| thyroid-stimulating hormone stimulation test | TSH stimulating test, a test that measures the uptake of 131I in the thyroid gland before and after administration of thyroid-stimulating hormone; useful in distinguishing primary hyperthyroidism (increased TSH serum concentration) from secondary or tertiary hyperthyroidism (low TSH serum concentrations). (05 Mar 2000) |
| 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) |
| thyroid veins | See: inferior thyroid vein, middle thyroid vein, superior thyroid vein, plexus thyroideus impar. (05 Mar 2000) |
| elevator muscle of thyroid gland | A fasciculus occasionally passing from the thyrohyoid muscle to the isthmus of the thyroid gland. Synonym: musculus levator glandulae thyroideae, elevator muscle of thyroid gland, Soemmerring's muscle. (05 Mar 2000) |
| fibrous capsule of thyroid gland | The fibrous sheath of the thyroid gland. Synonym: capsula fibrosa glandulae thyroideae. (05 Mar 2000) |