triiodothyronine

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Related to Free Triiodothyronine: free thyroxine, FT3, Ft³, Free T4

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 ?
The free Triiodothyronine T3 measurements showed no significant difference between the breast cancer groups, fibrocystic group and the normal healthy control group (p > 0.05).
Test Result Reference interval Thyroid-stimulating hormone 0.02 mIU/L 0.27-4.20 mIU/L Free thyroxine >77.4 ng/L 9.3-17.1 ng/L Free triiodothyronine 8.3 ng/L 2.0-4.4 ng/L
His blood test results were as follows: thyroid-stimulating hormone, 9.13 [micro]IU/mL; free triiodothyronine, 2.58 pg/mL; and free thyroxine, 1.01 ng/mL.
After the study was completed, free triiodothyronine (fT3) and total thyroxine (TT4) were measured with the stored blood at 0, 12, 26, and 52 weeks after the treatment.
Before operation, the patient's thyroid was normal without abnormal findings of thyroid ultrasonography, thyroid function tests (triiodothyronine, thyroxine, free triiodothyronine, free thyroxine, and hypersensitive thyrotropin), thyroid globulin, and relative thyroid antibodies (thyroglobulin antibody, thyroperoxidase antibody, TRAb).
Biochemical characteristics included serum concentrations of TSH, [fT.sub.4], and free triiodothyronine ([fT.sub.3]).
The normal range of free triiodothyronine is 1.7-4.2 pg/mL.
Clinical and paraclinical findings (free triiodothyronine, free thyroxine and thyroid stimulating hormone) were documented for all patients.
Thyroid profile showed thyroid stimulating hormone (TSH) levels to be 50 mIU/L (0.5-4.7); free thyroxine (FT4) to be 2.4pmol/L (10-23); and free triiodothyronine (FT3) to be 1.3 pmol/L (3.5-6.5).
Furthermore, thyroid-stimulating hormone (TSH) and free triiodothyronine ([FT.sub.3]) also have a circadian rhythm.
His free triiodothyronine (2.36–3.53 pg/ml), free thyroxine (8.6–13.3 ng/L), and thyroglobulin antibody (2.02–2.54 U/ml) were in the normal range during the whole process, but his thyroid peroxidase antibody (30.65–140.61 U/ml) and thyroid-stimulating hormone (5.6085–13.6435 [micro]U/ml) were elevated (all data were collected by SIEMENS ADVIA Centaur CP immunoassay system [Siemens 511, Benedict Avenue, Tarrytown, New York, USA]).