Thyroid & AntiThyroid Q's
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28 terms
Terms | Definitions |
|---|---|
 Thyroid Gland Hormones | Calcitonin, Thyroxine (T4), Triiodothyronine (T3) |
| Thyroid Hormone Synthesis & Secretion | uptake of circ iodid--> forms T3 & T4, secretion of T3 & T4, T4 convert to T3 by liver & kidney |
| Regulation of thyroid hormone synthesis/secretion | controlled by Hypothalamus, Ant. Pituitary, & Thyroid; TSH- released by Ant Pit, controls thyroid fxn--> prod of T3 & T4; TRH- produced by hypotalamus, acts on ant. Pit |
| What is TSH | released by Ant. Pit., controls thyroid fxn--> production of T3 & T4 |
| What is TRH | produced by hypothalamus, acts on ant. Pit. |
| MoA of T3 & T4 | inhibit hypothalamus & ant. Pit. To produce TSH & TRH--> too much iodide inhibits thyroid |
| MoA of thyroid hormones | activation of nuclear receptors attached to DNA leading to transcription of mRNA --> incr synthesis of specific proteins which produce effects; T3 is 10x more potent than T4 for binding receptors |
| Which is more potent in binding receptors, T3 or T4? | T3 is 10x more potent |
| Thyroid Hormone actions | T3 & T4 dissociated from thyroid binding proteins, free to enter cell, T4 converted to T3, T3 enters nucleus, binds to T3 receptor proteins (alpha & beta), different [] of the receptor form in different tissues |
| Effects of thyroid hormone | norm growth & development, incr BMR, thermogenic effect (incr heat prod), incr plasma glucose, plasma [], CV activity; maturation & development of CNS |
| Thyromimetic agents used to tx hypothyroidism | levothyroxin (T4), liothyronine (T3), liotrix (T3 & T4), thyroid |
| What is levothyroxine? | T4, available for inj, preferred for therapy- longer 1/2 life, long duration allows 1x/day therapy, better standardizaiton & stability |
| What is liothyronine? | T3, expensive, multiple daily dosing, harder to monitor |
| What is liotrix? | T3 & T4, increased cardiotoxicity |
| What is thyroid as a thyromimetic agent? | thyroid powder from animals, older prep no longer preferred |
| Antithyroid agents used to tx Hyperthyroidism | potassium iodid, radioiodide, thioamides (propylthiouracil, methimazole, carbimazole), beta-adrenergic antagonists, dilitiazem |
| Potassium iodid action as antithyroid agent | incr [] produce an autoinhibition of I uptkae, decr release of thyroid hormones |
| Uses of potassium iodide | axns occur in 207 days, given as saturated soln of KI or LUGOL's solution (rarely |
| Adverse effects of Potassium iodide | allergic rxn, iodism, not used long term |
| Action of radioiodide | destroys thyroid gland w/o injury to adjacent tissue at proper doses |
| Uses of radioiodide | hyperthyroidism, thyroid cancer |
| Adverse effects of radioiodide | delayed hypothyroidism |
| Action of thioamides | inhibit peroxidase enzymes catalyzing oxidation of I & coupling of iodinated tyrosel groups--> decr snthesis of thyroid hormones, C= prodrug of methimazole, converted to active drug inside body |
| Uses of thioamides | hyperthyroidism- delayed onset of meds by 3-4 weeks |
| Adverse effects of Thioamides | skin rxns, GI upset, agranulocytosis, goiter, hypothyroidism |
| Uses of beta-adrenergic antagoinsts as antithyroid agents | adjunct (propanolol, atenolol), control CV effects of hyperthyroidism |
| Dilitiazem action as antithyroid agent | Adjunct, Ca channel blocker |
| Uses of dilitiazem as antithyroid agent | adjunct, used to relieve supraventricular arrhythmias |
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