Term
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Definition
Metabolic homeostasis Development of the CNS and myelin |
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Term
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Definition
| Thyroxine (T4) and Triiodothyronine (T3) Iodinated tyrosine residues of thyroglobulin |
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Term
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Definition
| Used: to treat hyperthyroidism MOA: PTU blocks coupling. Coupling is the formation of T3 and T4 |
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Term
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Definition
Hypothalamus releases TRH à pituitary releasing TSH à thyroid gland T3 and T4
Dopamine and glucocoricoids can inhibit TSH as well |
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Term
| TSH solubility and transport: |
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Definition
| water soluble and binds extracellularlly to a G-Protein which activates a second messenger |
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Term
| Thyroid hormone product solubility: |
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Definition
| lipid soluble hormonesthat bond to nulcear receptors, and need carriers to transport |
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Term
| Effects of Thyroid Hormones: |
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Definition
1. Calorigenic- increase BMR
2. CNS development and function (myelin basic proteins)
3. Growth
4. Sympathomimetic effects- increase tissue responses to catecholamines. Stimulates the expression of beta 1 receptors , so tissues become more sensitive to catecholamines.
5. Metabolic- increases lipolysis, protein catabolism |
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Term
| side effects of catecholamine stimulation: |
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Definition
| tachycardia (because of overexpression of tachcardia). Was previously used for weigh loss, but people had heart attacks. |
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Term
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Definition
distinguishes 1o vs. 2o hypothyroidism (or simply measure TSH) this works because injecting TSH, if it is primary (a primary problem is the thyroid gland) we will still see low levels of T3 and T4.
secondary would be a problem with the pituitary. |
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Term
Hypothyroidism (myxedema coma, severe)
Symptoms: |
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Definition
a. mental retardation (cretinism) in infants
b. decreased BMR, cold intolerance bradyardia, lethargy, weight gain, ↓ growth (children) |
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Term
| secondary hypothyroidism signs and symptoms: |
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Definition
| Thyroid gland enlarges to compensate and a goiter is formed. Entire neck looks swollen |
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Term
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Definition
levothyroxine sodium
Advantages: drug of choice for replacement therapy - oral or iv preparations
Pharmacokinetics: T4 is given and not T3 because T4 is inactive and converted to T3 the active form. The body regulates the conversion of T4 to T3. This way we can ensure we don’t induce hyperthyroidism. |
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Term
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Definition
liothyronine sodium
PK:short half-life and duration of action - oral or iv
Ts is active so it can cause hyperthyroidism
Test question: Use T4 because it has to be convertd to T3. This makes the body regulate the levels because of the conversion, so there is a decrease in the possiblity of having hyperthyroidism.
A: T4 because it has to be converted to T3 (test quesiton)
Mixture of T4 and T3 - no therapeutic advantage over T4
Side effects: (of all above)- usually caused by overdose
a. Hyperthyroid symptoms
b. Stimulates metabolism of many drugs
Side affects are caused by T3 (active form) can lead to an overdose and gives rise to the side effects. This can induce hyperthyroidism |
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Term
| hyperthyroidism symptoms: |
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Definition
Sympoms: increased BMR,heat intolerance, excessive perspiration, muscle wasting, weakness, nervousness, tachycardia, arrhythmias, weight loss, bone loss
Causes: a. Autoimmune (Graves disease) - Thyroid receptor antibodies (TRAb) or LATS (long-acting thyroid stimulator) hypersecretion exopthalmus |
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Term
old hyperthyroidism treatments:
(not used much anymore) |
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Definition
a. Subtotal thyroidectomy - may lead to hypothyroidism
b. 131I (destruction of thyroid tissue) – can cause hypothyroidism- not used much anymore |
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Term
| Inhibitors of thyroid hormone synthesis: |
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Definition
| Thioamides- block iodide incorporation into thyroglobulin and coupling of iodotyrosines - effects not seen until hormone stores depleted. |
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Term
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Definition
MOA: also inhibits peripheral monodeiodination of T4 → T3
-good to use because it is only converted to active form when needed |
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Term
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Definition
MOA: does not inhibit conversion of T4 to T3
PK: longer half-life than PTU and 20 x more potent than
Inhibitor of the synthesis of thyroid hormones is used often. used. Blocks incorporation in the first step using hormones.????
MMI does not block the conversion of T4 to T3.
Side effects: (of all?) - skin rPTU and MMI (beginning of lecture) are ash, granulocytopenia, agranulocytosis, goiter ( TSH), arthritis |
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Term
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Definition
high amounts inhibit iodine formation and block hormone release - used with thioamides preoperatively or for several weeks after 131 I treatment. This is used prior to surgery, this is used to block the activity of the thyroid gland
Preparations available: potassium iodide tablets and Logol's solution - oral or iv |
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Term
| Lithium Carbonate therapy: |
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Definition
| MOA: blocks hormone release |
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Term
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Definition
| Propranolol hydrochloride - alleviates many signs and symptoms of hyperthyroidism - used largely as adjuvant |
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Term
| Drug Interactions with Thyroid |
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Definition
A. Estrogens increaseTBG (thyroid binding globulin)synthesis
B. Salicylates- compete for binding to serum proteins
C.Catecholamines- in combination with thyroid hormones cause cardiovascular toxicity
D. T4 & T3 - effects on drug metabolism |
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