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.
Cortisol
Daily avg secreted
High stress
10-20 mg
50-150 mg
Cortisol
1/2 t
Metab exc
1.5-3 hrs, longer fx
Liver, urine unchanged
Methylprednisone used for
HPA axis depression replacement
Betamethasone lacks
Mineralcorticoid fx
Dexamethasone uses 3
Cerebral edema, antiemetic, airway edema control periop
Triamcinolone
Use
Epidural injections LBP
Prednisolone
Fx
Which is converted to it
Mineral and glucocorticoid
Prednisone converted to prednisolone after absorption
Adrenal insufficiency
Drug & dose for acute
What must be eval tx too
Cortisol 100 mg q8
F&E imbalances
Adrenal ins
Chronic drug and dose
Needs what also
Cortisone 25 mg q am 12.5 in afternoon Mineralcorticoid added (ex fludrocortisone)
IV glucocorticoids fx
1 hr
4-6h
Beta adrenergic agonist enhancement
Antiinflammatory
Steroid for allergy and asthma
Glucocorticoids iv
Chronic asthma tx first line bronchospasm prevention
Inhaled glucocorticoids via MDI. Beclomethasone, triamcinolone, flunisolide
SE inhaled glucocorticoids
Dysphagia (laryngeal muscle myopathy)
HPA axis disturbance if daily dose >1500 mcg adults 400 peds
Decadron
Dose
E 1/2t
Given when
8-10 mg
3 hrs, antiemetic for 24h
Shortly after induction
Post op __ effect w glucocorticoids how
Inhib cyclooxygenase and lipoxygenase path has analgesic effect
Steroid use in IC tumors
ICP and edema control. Not for CHI
Steroid not strongly effective for
Aspiration pneumonitis
Steroid use in lumbar disc herniation
Epidural injection to reduce edema and inflammation at nerve root
Steroid and dose for lumbar disc hern
HPA axis sup how long after
25-50 triamcinolone
40-80 methylpred
1-3 months
Steroids prevent what in premies
RDS, given to mothers threatening labor <37 weeks
SE steroids
HPA exis sup (CV collapse), FE imb, infec, osteoporosis, PUD, skel musc weak, psych disorders, CBC changes, growth retard in kids, dec anticoag effectiveness
Conditions needing periop steroid coverage
Addisons. Hypotension, hyponatremia, hyperkalemia, eosinophilia. Risk based on therapy.
Steroid dose for minor surgery
Preop plus hydrocortisone 25 mg
Steroid dose for moderate sx
Preop plus hydrocortisone 50-75 mg
Steroid dose for major surgery
Preop, 100-150 every 8hrs for 48-72hrs
Glucagon- hormone for what
Hyperglycemic. Made by alpha cells in pancreas and upper gi in resp to hypoglucemia or inc plasma proteins
Glucagon
Enhances what two things
Formation of camp and release of catecholamines
Glucagon
Inc: 6
Dec:1
Relaxes what
Inc contractility, hr, renal bf, insulin sec, gluconeogenesis/glycogenolysis
Gastric motility
Smooth muscle (sphincters)
Glucagon does what to vessels
Vasodilates, dec SVR
Glucagon dose
1-5 mg iv
5 mcg/kg/min (20/hr)
Glucagon cv effects
Inc co (w bb), improves low CO (post mi/Cpb), imp CHF symp, enhances AV conduc (dig toxicity)
Glucagon
Use in dx of
Use in placement of
Pheochromocytoma
Biliary stents- causes dilation
Glucagon SE
High or low bg, low K, NV, abrupt hr inc in afib
Somatostatin is what
Gi regulatory peptide sec by panc delta cells
Ocreotide is what
Somatostatin analogie. Both inhib produc/rel of hormones from GI/pancreas
Ocreotide inhib rel of
GH, insulin sec, glucagon, VIP
Somatostatin ocreotide 1/2t
3 min, 2.5 min
Ocreotide used for
Carcinoid crisis (dec rel of serotonin/vasoactives) Hepatorenal syndrome Control of varices bleed
What is possible w ocreotide bolus
Bradycardia, 2nd or 3rd degree heart block
ADH
Receptor classes/actions
Inc rel of
V1- arterial smooth muscle vasoconstriction
V2- inc h20 perm reabs collecting ducts
V3- inc acth release
ADH e 1/2
10-20 min
Vasopressin uses 4
DI (central)
Varicies
Hemorrhagic/septic shock
Cv arrest resusc
Vaso SE
Inc bp (larger doses) Coronary artery vasoconstriction (angina, mi, ischemia, ecg changes, arrhythmias) Gi hyperperistalsis (NV, abd pain)
DDAVP
Comparison to vaso
E 1/2 2-4h
More selective for v2/antidiuretic than v1 (vasoconstriction). Better for DI.
DDAVP
Stim release of
Endothelial cells to inc sec of VWF, tpa, and prostaglandins
Synthetic oxytocin
Acts on what to cause contraction
Uterus, induces labor, dec post partum
Oxytocin
In high doses what can happen
SVR dec reducing SBP and DBP. H20 retention.
Oral bc
Estrogen prev
Progesterone prev
FSH release
LH release
SE from bc
Thromboembolism (plt agg and clotting factors by estrogen), MI and stroke risk, htn
