triiodothyronine


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triiodothyronine

 [tri″i-o″do-thi´ro-nēn]
a thyroid hormone that contains iodine and is liberated from thyroglobulin by hydrolysis. It has several times the biologic activity of thyroxine.
free triiodothyronine the fraction of triiodothyronine in the serum that is not bound to a binding protein.
triiodothyronine resin uptake test a thyroid function test, measuring how many sites on thyroxine-binding globulin (TBG) are occupied by endogenous triiodothyronine (T3) and how many sites remain available. An excess of radioactive exogenous triiodothyronine is added to the sample, followed by the addition of a resin that also binds T3. A portion of the radioactive T3 binds to sites on TBG not already occupied by endogenous thyroid hormones, and the remainder binds to the resin. The amount of labeled hormones bound to the resin (the triiodothyronine resin uptake) can be subtracted from the total that was added and the remainder is the amount that bound to the unoccupied binding sites on the thyroxine-binding globulin.

triiodothyronine

(trī′ī-ō′dō-thī′rə-nēn′, -ī-ŏd′ō-)
n.
A thyroid hormone, C15H12I3NO4, similar to thyroxine but more potent, used in the treatment of hypothyroidism.

triiodothyronine

T3, 3,5,3´,-´triiodothyronine A hormone formed by removing an iodine ion from the chemical parent thyroxine–T4, which occurs in the liver and kidney; in general, the T3 and T4 serum levels rise and fall together with certain exceptions–eg, T3 thyrotoxicosis, in which T4 and free T4 values are in the normal range; most T3 is not bound to a carrier protein in the circulation ↑ in Hyperthyroidism–T3 thyrotoxicosis, pregnancy, and therapy with clofibrate,–oral contraceptives–progestins, estrogens, methadone, perphenazine ↓ in Euthyroid sick syndrome, ↑ free fatty acids, hypothyroidism, malnutrition, or therapy with corticosteroids, ethionamide, heparin, iodides, lithium, methimazole, phenylbutazone, phenytoin, propranolol, propylthiouracil, reserpine, salicylates, sulfonamides, testosterone, tolbutamide; Pts with T3 thyrotoxicosis are clinically heterogeneous and lack distinctive signs and Sx, comprising 4% of hyperthyroid Pts due to Graves' disease, toxic nodular goiter and thyroid adenomas and a higher percentage of hyperthyroidism in regions with lower levels of iodine Ref value 0.92-2.46 nmol/L; 60-160 ng/dL. See Thyroxine–T4, Thyroxine-binding globulin, TSH.
References in periodicals archive ?
Association between increased levels of reverse triiodothyronine and mortality after acute myocardial infarction.
The serum triiodothyronine T3 was significantly higher in the breast cancer post-treatment patients compared to the controls.
Fang et al., "Free triiodothyronine level correlates with myocardial injury and prognosis in idiopathic
And Serum Thyroid stimulating hormone (TSH), serum total triiodothyronine (TT3), serum total thyroxine (TT4), level were estimated by chemiluminescence method (using ARCHITECT i1000sr Immunoassay system- ABBOTT).
(2012; 2015) reported a positive correlation of ambient temperature and a negative correlation of triiodothyronine ([T.sub.3]) with MRT of digesta.
The patient had purchased the product, which contained triiodothyronine (a thyroid hormone), online.
Thyroid tests should be obtained before the medication is taken because triiodothyronine levels rise abruptly in response to a dose.
The two main thyroid hormones produced by the thyroid gland are triiodothyronine and levothyroxine, which are called T3 and T4 respectively.
Laboratory testing revealed normal thyroid-stimulating hormone, triiodothyronine (T3), and free thyroxin (T4) levels.
The thyroid is a butterfly–shaped gland in your neck that produces the hormones thyroxine and triiodothyronine, vital for controlling your metabolism.
Newborn rats were assigned to groups of 6 rats each for subcutaneous (sc) injection of 0.5, 1.0, 1.5, 2.0, 4.0, or 50.0 [micro]g/100 g body weight (BW) triiodothyronine ([T.sub.3]; Sigma, USA; Hyper-5 group), groups of 12 rats each for sc injection of 5 or 10 mg/100 g BW propylthiouracil (PTU; Sigma; Hypo-5 group), or saline (0.9% NaCl; Control-5 group), for 5 days beginning on P1.