Thyroid Hormones and Anti-Thyroid Agents

The primary hormones released by the thyroid gland are tetraiodothyronine (T4) and triiodothyronine (T3).

Goiter refers to the enlargement of the thyroid gland from any cause.

Calcitonin is needed for the regulation of calcium metabolism.

<p>Iodine is essential for the synthesis of thyroid hormones T4 and T3.</p> Signup and view all the answers

<p>Thyroid hormones regulate the resting metabolic rate of most tissues.</p> Signup and view all the answers

<p>Thyroid hormone deficiency early in life can lead to irreversible mental retardation and dwarfism.</p> Signup and view all the answers

<p>Common problems include underactivity (hypothyroidism) and overactivity (hyperthyroidism).</p> Signup and view all the answers

<p>Hyperactivity of the thyroid gland produces effects similar to sympathetic nervous system overactivity.</p> Signup and view all the answers

<p>Free T4 and TSH levels must be within normal levels.</p> Signup and view all the answers

<p>Levothyroxine is the most prescribed preparation.</p> Signup and view all the answers

<p>Liothyronine has a shorter half-life and necessitates multiple daily dosing.</p> Signup and view all the answers

<p>Disadvantages include protein antigenicity and variable hormone concentration.</p> Signup and view all the answers

<p>Levothyroxine is administered once daily orally.</p> Signup and view all the answers

<p>Liothyronine poses a greater risk of cardio toxicity.</p> Signup and view all the answers

<p>The shelf life is about 2 years when stored properly.</p> Signup and view all the answers

<p>Toxicity seen with levothyroxine is directly related to hormone level.</p> Signup and view all the answers

<p>Thioamides primarily inhibit the coupling of iodotyrosines, blocking thyroid hormone synthesis.</p> Signup and view all the answers

<p>A common adverse effect is a maculopapular pruritic rash.</p> Signup and view all the answers

<p>Anion inhibitors such as perchlorate competitively block iodide uptake by the thyroid gland.</p> Signup and view all the answers

<p>Potassium perchlorate is useful for treating iodide-induced hyperthyroidism, like that caused by amiodarone.</p> Signup and view all the answers

<p>Iodides inhibit organification and hormone release, and can reduce the size and vascularity of the thyroid gland.</p> Signup and view all the answers

<p>Iodides should be administered at less than 6 mg daily.</p> Signup and view all the answers

<p>Cross-sensitivity within thioamides may lead to severe reactions if a patient switches between them.</p> Signup and view all the answers

<p>A significant rare adverse effect is aplastic anemia.</p> Signup and view all the answers

<p>Iodide trapping is the transport of iodide into the thyroid gland, and it can be inhibited by anions such as SCN^- and TCO4^-.</p> Signup and view all the answers

<p>Thyroidal peroxidase oxidizes iodide to iodine, a step that can be inhibited by thioamides and excess iodide.</p> Signup and view all the answers

<p>Iodine organification refers to the iodinates of tyrosine residues in thyroglobulin, forming monoiodotyrosine (MIT) and diiodotyrosine (DIT).</p> Signup and view all the answers

<p>Two molecules of DIT combine to form L-thyroxine (T4), while one molecule of MIT and one molecule of DIT form triiodothyronine (T3).</p> Signup and view all the answers

<p>High levels of iodide within the gland can inhibit the proteolysis required for the release of thyroid hormones from thyroglobulin.</p> Signup and view all the answers

<p>T4 and T3 are primarily transported in plasma bound to thyroxine binding globulin (TBG).</p> Signup and view all the answers

<p>Thyroxine is metabolized mainly through deiodination, leading to the formation of T3, and can also be inactivated via deamination or conjugation.</p> Signup and view all the answers

<p>The transport of T4 and T3 via TBG can be inhibited by drugs, physiologic conditions, and pathologic states.</p> Signup and view all the answers

<p>Radiation can induce genetic damage, leukemia, and neoplasms, particularly in patients over 40 years old.</p> Signup and view all the answers

<p>Beta blockers mimic sympathetic stimulation and help alleviate symptoms associated with thyrotoxicosis.</p> Signup and view all the answers

<p>A thyroid storm is a sudden acute exacerbation of all symptoms of thyrotoxicosis, which can be life threatening due to its severity.</p> Signup and view all the answers

<p>Propranolol and saturated potassium iodide are two treatments given during a thyroid storm.</p> Signup and view all the answers

<p>Subtotal thyroidectomy is recommended for women of child-bearing age with thyrotoxicosis.</p> Signup and view all the answers

<p>Corticosteroids like hydrocortisone protect against shock and block the conversion of T4 to T3.</p> Signup and view all the answers

<p>Iodinated contrast blocks the peripheral conversion of T4 to T3, helping to manage hormone levels.</p> Signup and view all the answers

<p>Radiation poses significant risks to the developing fetus and nursing infants.</p> Signup and view all the answers