Hormones liothyronine

Levothyroxine is used to treat hypothyroidism (an underactive thyroid gland). Thyroid hormone can be made from beef and pork thyroid, but this lacks standardization and it is difficult to control dosage. The synthetic drug is more desirable. Levothyroxine is one of two important thyroid hormones. It is converted into the second important hormone, liothyronine, in the body. The key step in the synthesis of structures such as levothyroxine is the substitution of an iodonium salt by an iodinated phenol. Siql-like reactions on an aromatic ring are not common, but an iodonium salt provides a good leaving group. 

Ohio State University Recombinant human thyroid-stimulating hormone Liothyronine Levo thyroxine Thyroglobulin Anti-thyroglobulin antibody Thyroid-stimulating hormone (Thyrotropin)... 

Immediate and aggressive therapy with IV bolus levothyroxine, 300 to 500 meg, has traditionally been used. Initial treatment with IV liothyronine or a combination of both hormones has also been advocated because of impaired conversion of T4 to T3. 

Liothyronine sodium (Cytomel) is the sodium salt of the naturally occurring levorotatory isomer of T3. Liothyronine is generally not used for maintenance thyroid hormone replacement therapy because of its short plasma half-life and duration of action. The use of T3 alone is recommended only in special situations, such as in the initial therapy of myxedema and myxedema coma and the short-term suppression of TSH in patients undergoing surgery for thyroid cancer. The use of T3 alone may also be useful in patients with the rare condition of 5 -deiodinase deficiency who cannot convert T4 to T3. 

Liotrix (Euthroid, Thywlar) is a 4 1 mixture of levothyroxine sodium and liothyronine sodium. Like levothyroxine, liotrix is used for thyroid hormone replacement therapy in hypothyroid patients. Although the idea of combining T4 and T3 in replacement therapy so as to mimic the normal ratio secreted by the thyroid gland is not new, it does not appear that liotrix offers any therapeutic advantage over levothyroxine alone. 

Mechanism of Action A natural hormone derived from animal sources, usually beef or pork, fhat is involved in normal mefabolism, growfh, and development, especially the central nervous system (CNS) of infanfs. Possesses cafabolic and anabolic effecfs. Provides both levothyroxine and liothyronine hormones. Therapeutic Effect Increases basal metabolic rate, enhances gluconeogenesis, stimulates protein synthesis. 

Thyroid hormones levothyroxine sodium liothyronine sodium thyroid... 

Although liothyronine (T3) is three to four times more potent than levothyroxine, it is not recommended for routine replacement therapy because of its shorter half-life (24 hours), which requires multiple daily doses its higher cost and the greater difficulty of monitoring its adequacy of replacement by conventional laboratory tests. Furthermore, because of its greater hormone activity and consequent greater risk of cardiotoxicity, T3 should be avoided in patients with cardiac disease. 

Fever, liver dysfunction, and eosinophilia occurred during liothyronine or levothyroxine treatment of a hypothyroid patient and disappeared after withdrawal of therapy (47). In vitro lymphocyte testing confirmed sensitization for thyroid hormones. 

It is likely that in this case long-standing suppression of pituitary function secondary to negative feedback from exogenous hormone ingestion (including liothyronine) resulted in pituitary atrophy. 

Escobar-Morreale HF, Botella-Carretero JI, Gomez-Bueno M, et al. Thyroid hormone replacement therapy in primary hypothyroidism a randomized trial comparing L-thyroxine plus liothyronine with L-thyroxine alone. Ann Intern Med. 2005 142 412-424. 

The use of desiccated thyroid rather than synthetic preparations is never justified, since the disadvantages of protein antigenicity, product instability, variable hormone concentrations, and difficulty in laboratory monitoring far outweigh the advantage of low cost. Significant amounts of T3 found in some thyroid extracts and liotrix may produce significant elevations in T3 levels and toxicity. Equivalent doses are 100 mg (1.5 g) of desiccated thyroid, 100 Mg of levothyroxine, and 37.5 ug of liothyronine. 

Cytomel Liothyronine 5, 25, 50 JLg Tablet Hupothyroidism, Hormone, TSH Calcium sulfate, gelatin, starch, King Pharmaceu-... 

Blood concentrations of levothyroxine (T4), liothyronine (T3) and thyroid stimulating hormone (TSH) need to be taken. 

Steroids, hormones, and related compounds betamethasone, dexamethasone, dienoeshol, ethinyl-oestradiol, ethynodiol diacetate, fludrocortisone, liothyronine, lynoestrenol, mestranol, norethister-one, stilboestrol, thyroxine. 

L-thyroxine (T j or tetraiodo-L-thyronine) and liothyronine (Tg or triiodo-L-thyronine) are the natural hormones of the thyroid gland. is a less active precursor of Tj, which is the major mediator of physiological effect. In this chapter for therapeutic use is referred to as levothyroxine (the rINN, see p. 83) rather than levothyroxine (the former usage). 

Liothyronine Tabs. Liothyronine is the most rapidly effective thyroid hormone, a single dose giving maximum effect within 24 h and passing off over 24—48 h. It is not used in routine treatment of hypothyroidism because its rapid onset of effect can induce heart failure. Its main uses are in myxoedema coma and psychosis, both rare conditions. A specialised use is during the withdrawal of levothyroxine replacement (to permit diagnostic radioiodine scanning) in patients with thyroid carcinoma. 

Myxoedema coma follows prolonged total hormone deficiency and constitutes an emergency. Intravenous therapy is mandatory because of impaired absorption of drugs in this condition. Liothyronine 5-20 micrograms is given every 12 hours. Hydrocortisone i.v. is also needed, as prolonged hypothyroidism may be associated with adrenocortical insufficiency. 

Synonyms Dry thyroid Desiccated thyroid Thy-reoidin Thyroid Strong, Thyroglobin Chemical/Pharmaceutical/Other Class Natural hormone that provides a mixture of levothyroxine (T4) and liothyronine (T3)... 

Liothyronine sodium is a thyroid hormone that increases metabolic rate of body tissues and is needed for normal growth and maturation. It is indicated for the replacement or supplemental therapy in hypothyroidism in TSH suppression for treatment or prevention of euthyroid goiters (e.g., thyroid nodules, multinodular goiters, enlargement in chronic thyroiditis) and as a diagnostic agent in suppression tests to differentiate suspected hyperthyroidism from euthyroidism and in treatment of myxedema coma/precoma (IV). 

The synthetic preparations used are the sodium salts of the natural isomers of the thyroid hormones. Levothyroxine sodium (L-T, synthroid, levoxyl, levothroid, unithroid, others) is available in tablets in a variety of doses and as a lyophilized powder for injection. L-T has a narrow therapeutic index, and the FDA has mandated demonstration of bioequivalence for brand and generic preparations by the various producers. Liothyronine sodium (L-Tft is available in tablets (cytomel) and in an injectable form (triostat). A mixture of L-T and L-T is marketed as liotrix (thyroiar). Desiccated thyroid preparations, derived from whole animal thyroids and containing both T and T have highly variable biologic activity and are much less desirable. 

The understanding of structure-activity relationships also enabled the development of synthetic T3 (liothyronine), the metabolically more active form of thyroid hormone with a much shorter duration of action. This is especially useful for patients with thyroid carcinoma who are to undergo radioiodine imaging and possible treatment. Because of a half-life of only 24 hours, liothyronine substitution enables timelier radioiodine imaging and treatment, and as a result, patients experience less symptomatic hypothyroidism. 

The nurse is preparing to administer liothyronine (Cytomel), a thyroid hormone, to a client diagnosed with hypothyroidism. Which data would cause the nurse to question administering the medication ... 

Thyroid hormone is available as synthetic triiodothyronine (T3, or liothyronine), synthetic tetraiodothyronine (T4, levothyroxine), or natural desiccated animal thyroid (containing both T3 and T4 Table 11-55). Despite concern over the potentially life-threatening manifestations of thyrotoxicosis, serious toxicity rarely occurs after acute thyroid hormone ingestion. 

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