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36 Cards in this Set
- Front
- Back
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what two hormones does the thyroid gland secret?
what peptide does it secrete? |
1. thyroxine(T4)
2. triiodothyroninT3) peptide=calcitonin |
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what the most active form of TH?
what do the thyroid drugs control? |
T3 is most active form
thyroid contributres to normal growth and development though maintenance of normal tissue metabolism. |
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what is calcitonin used to control?
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calcium metabolism
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is the thyroid gland vital for survivial?
what can low levels of circulating thyroid hormone cause(what are assoc symptoms? |
Not vital for survivial
low levels are hypothyroidism which can produce bradycardia, decreased resisitance to cold as well as physical and intellectual deficiency |
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what can hypothyroidism lead to in kids?
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hypothyroidism can lead to:
-mental retardation -cretinism(stunted mental and physical growth) -dwarfism |
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what can hyperthyroidism cause?
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sympathetic nervous hyperactivity:
-hyperactivity -tachycardia -cardiac arrythmia -nervousness, tremor, body wasting -increased heat production |
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what are the three clinical uses of thryoid agonist drugs?
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1. replacement therapy(myxedema)
2. pituitary TSH suppression 3. ddx dx of hyperthyroidism |
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what are the clinical uses of antagonist thyroid drugs?
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1. treat graves dz(thyroxtoxicosis)
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what is the L-Thyroxin (t4) molecule made of?
what is the Triiodothyronine(T3) made of? what is required to synthesize both of these hormones? |
T4=two molecules DIT
T3=comprised of one molecule of MIT and one DIT iodine |
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where is iodine obtainedfrom?
is the uptake an active or passive process of iodine? what is iodinated in the gland to form MIT and DIT? what is the adverse effect of insufficient iodine uptake? |
food or supplements
uptake is active process tyrosine goiter |
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what type of effect does t3 and t4 have on hypothalamic release of TRH?
what stimulates the making of T3 and T4? |
negative feeback
TSH stimulates thyroid gland |
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what is grave's dz?
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an autoimmune dz where lymphocytes release a thyroid stimulating immunoglobulin.
This induces thyrotoxicosis |
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will elevated iodide concentrations inhibit or stimulate tyrosine?
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inhibits tyrosine
is employed in tx of hyperthyroidism |
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how do thyroid hormones control expression of genes responsible for several metabolic processes?
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nuclear receptors through genomic mechanism:
1. enter target cell 2. T4 converts to T3 3. T3 enters nucleus 4. binding to and activation fo specific nuclear receptro 5. dimerization of activated complex 6. activated dimer binds to nuclear repsonse elements 7. regulates transcription of target genes |
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what are monomeric forms of T3 nuclear receptors?
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alpha and beta that form into d dimers
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what is the most common cause of hypothyroidsim in the US?
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hashimoto's thyroidits
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what is drug of choice to treat myxedema?
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T4 drugs(Levothyroxine)
-SYnthroid#1 -Levoxyl#2 -Levothroid#3 |
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what are benefits of T4 over T3?
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longer half life and lower cost
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what are T3 drugs used?
what is a PO drug what is a IV drug |
Liothyronine
PO=cytomel IV=triostat |
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what is the outcome of unmanaged hypothyroidism?
how is this managed? |
myxedema coma
managed with IV triostate |
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what are major side effects of T4 and T3 tx?
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similar to thyrotoxicosis
*tachycardia *heart palpitations *nervousnell *heat intolerance |
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how is T3 and T4 normally administered?
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PO
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how are T3 and T4 metabolized?
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T4 converted by 5prime Deiodinase
metabolized via microsomal P450 enzymes |
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what drugs will increse metabolism of thyroid drugs causing a need for increased dosage?
what condition will cause increased need of dosage? |
1. Phenytoin
2. Phenobarbital 3. Rifampin pregnancy |
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what are the antithyroid drugs used to tx?
what are three ways to achieve this? |
graves
1. surgical removal of gland 2. inhibit release of hormone 3. block hormone synthesis |
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what are S&S of graves?
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*increased sympathetic
-hyperglycemia -muscle weakness and fatigue -exopthalmos |
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how is thryoid surgically removed?
what is dose? when is this the preferred therapy? what is major disad? what are c/is |
by use of radioactive iodine
give 4-15mci favored therapy for patients OVER 21 major disad is delayed hypothyroidism c/is are pregnant or nursing females |
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what are drugs used to inhibit thryoid hormone syntehsis?
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The thioamides
1. Propylthiouracil(PTU) 2. Methiamzole(Tapazole) |
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when are thioamides the preferred therapy?
which one of the thioamides is safest for use during pregnancy? |
for patients under 21
PTU is safest while pregnant |
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what is mechanism of action of thiamides?
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inhibit thyroid peroxidase by blocking oxidation rxns necessary for iodination of tyrosine residues of thryroglobuline
(high doses also block t4-t3_ |
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what are the adverese effects of thioamides?
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*skin rash
*AGRANULOCYTOSIS(lack of leukocytes) *hepatotoxicity, jaundice |
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what are drugs used to block thryoid hormone synthesis?
how are these drugs administered? |
iodide salts
orally |
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what are solutions of iodide salts used?
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1. Lugol's solution
2. Saturation solution of Kiodide(SSKI) |
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what is mechanism of action of these drugs?
how does onset of these drugs compare to thioamides? |
* inhibit both release and synthesis of thyroid hormones
rapid onset(faster) |
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what are clinical indications for use of these drugs?
what are the adverse effects? |
thyroid storm (severe thryotoxicosis)
adverse: -allergic rxn -fetal goiter |
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what are other durgs useful in managing tachycardia and other cardiac abnormalities of thyroid storm?
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Beta blockers (propranolol)
CCB's (when BB's c/i) |
