Endocrine 2 Flashcards
Structure
T4
T3
4- 4 iodines to tyrosine backbone
3- 3 iodines, more active form
Process of thyroid hormone release
Hypothalamus rel TRH. TRH causes TSH rel from ant pit. TSH acts on thyroid- sec more T4/3
Thyroid sec more of what, which is converted in periphery
T4
Graves- what’s affected
TSH receptor activated.
How antithyroid drugs work
Competes w thyroglobulin for oxidized iodine. Reduced synthesis of thyroid hormones
Anti thyroid drugs onset, only useful when
1-2 weeks. Overproduction of thyroid hormones
PTU/methimazole
Can lead to what
Other 2 SE
Goiter- up reg TSH release, stim gland hypertrophy. Pruritic rash and arthralgias
3 serious complic of antithyroid drugs
Agranulocytosis 1st 90d (WBC monitor if fever/sore throat). Hepatotoxic. Vasculitis (drug ind lupus)
Which antithyroid drug preferred and why
Methimazole. Longer 1/2 life, take 1 qd, more potent than ptu, less freq serious SE
PTU
Also inhib what
Dosing
SE
T4 conversion in periphery. TID dosing.
Deplete PT- bleeds.
PTU
Preferred in
Route
Pregnancy or acute management in thyroid storm due to inhib T4 conversion.
NG for intraop thyroid storm
3 other tx hyperthyroidism
Thioamines works in 6-12 mos. I 131 ablation. Surgical removal and thyroid replacement
Use what while waiting for thioamines to work
Does what
Which one for thyroid storm
B blockers. Blocks tachycardia, tremor, conversion t4 to T3.
Esmolol, 9 min 1/2 t
How corticosteroids work hyperthyroidism
2 ones
Symptomatic tx, blocks t4 conversion, suppressor thyroid receptor Ab and inflammation.
Pred or methylpred
How lugols solution works
Blocks t4 conversion in hyperthyroid. Dec vascularity of gland. Temporarily blocks thyroid hormone release. Temporary tx
How hashimotos works
Causes of iatrogenic hypothyroid
Autoimmune antibodies against thyroid gland proteins. Blocks production of thyroid hormone.
Iatrogenic, pit tumor, sx
Levothyroxine
1/2 life
Monitor what
SE
7 days, once daily dosing
Tsh, free t4, s/s of hyperthyroidism
Allergic rash
When T3 used
Life threatening hypothyroidism (myxedema coma) where faster onset is useful
Which 4 drugs increase levothyroxine metab
Phenobarbital, phenytoin, rifampin, carbamazepine
Which drugs dec t4 to T3 conversion 4 (interact w levothyroxine)
Ptu, BB, amio, glucocorticoids
Levothyroxine decreases abs of what in gut 5
Cholestyramine, feso4, al(oh)3, sucralfate, kayexalate
Levothyroxine increases what (hormone interaction)
Thyroid binding globulin (binds T3, t4) in pregnancy, estrogen (OCs or HRT)
Drugs that alter thyroid status 3
Amio (cont iodine, hypo or hyper)
Lithium (can lead to hypo)
Reglan (inc tsh prod/rel)
Natural steroids 3
Cortisol, cortisone, aldosterone
Synthetic steroids 4
Prednisolone, prednisone, methylprednisolone, dexamethasone
Corticosteroid mineralcorticoid effects
Reabs na excretion k in renal distal tubule (aldosterone)
Glucocorticoid fx of steroids
Antiinflammatory, augment sustained sns activity in stress
Corticosteroids all have what in structure. Alterations in it act for what
Same steroid nucleus. Potency, abs, pb, metab
Where mineralcorticoid and glucocorticoid receptors found
Mineral- excretion organs: colon, salivary glands, sweat glands, kidney, hippocampus. Gluc- widespread
MOA steroids
Steroid and receptor enter nucleus, inf dna transcription= more/less protein synthesis/exp of certain genes
Steroid
Metabolic fx due to
Inc in nutrient availability by raising BG, AA, and TG levels
Steroid moa
How inflammatory response inhib
Phospholipase A2 inhib, arachidonic acid formation decreased.