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53 Cards in this Set
- Front
- Back
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What are 3 main causes of hypothyroidism?
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Hashimoto's thyroiditis
thyroidectomy radioactive iodine |
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How long does it take to achieve steady state of levothyroxine?
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about 4 wks
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Which pts should be started on a lower levothyroxine dose?
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>50 or with cardiac disease
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How should synthroid be taken?
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empty stomach with full glass of water at least 30 min before breatkfast
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What might decrease the absorption of synthroid?
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dietary fiber or soy protein supplements
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When will the pt typically get resolution of symptoms after starting levothyroxine?
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2-3wks; but check in 4-6
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In which pts is the TSH misleading/worthless?
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those w/central hypothyroidism (from hypothalamic or pituitary disease)
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What are ADRs of levothyroxine?
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s&s of hyperthyroidism (tremors, palpitations, anxiety, weight loss, tachycardia, inc bowel movements)
cardiac arrythmias, angina, or MI, afib, osteoporosis (depending on risk factors/age/length of tx) |
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What is liothyronine?
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LT3
shorter half-life than levothyroxine not recommended |
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What is thyroid USP?
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Armour thyroid - desiccated porcine thyroid tissue
100mcg of levothyroxine = 60mg (1grain) of armour don't use it |
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What happens to free T4 in pg? what does this mean for tx?
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decreases b/c elevated estrogen -> dec hepatic clearance of TBG; inc requirement for levothyroxine
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how do you treat myxedema coma?
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large doses of synthroid (sometimes use levothyroxine liothyronine combo in this case)
may also need hydrocortisone to avoid adrenal crisis |
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What is the most common cause of hyperthyroidism?
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Grave's disease (autoimmune)
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What is more commonly used, antithyroid drugs or radioactive iodine tx?
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radioactive iodine
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What are the two antithyroid drugs?
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propylthiouracil (PTU) and methimazole
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What class are PTU and methimazole in?
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thionamides
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How do the thionamides work?
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inhibit synthesis of thyroid hormone
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Which thionamide interferes with conversion of T4 -> T3 at high doses?
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PTU
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Why is methimazole generally preferred over PTU?
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can be given qd (instead of bid or tid like PTU)
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What are the ADRs of thionamides?
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agranulocytosis
polyarthritis immunoallergic hepatitis (only PTU) ANCA positive vasculitis w/acute renal failure (PTU usually) rash GI intolerance |
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What do you order if a pt taking a thionamide presents w/sore throat or fever?
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CBC (b/c worried about agranulocytosis)
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What do PTU and methimazole do to warfarin?
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decrease effect -> need higher dose of warfarin
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What might high concentrations of iodine be used for in thyroid tx?
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severe thyrotoxicosis
thyroid storm (rapid effects) |
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What is the treatment of choice for hyperthyroidism in pg?
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PTU
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Do thionamides cross the placenta?
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yes
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What are the classic symptoms of thyroid storm?
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fever, agitation, psychosis, tachycardia (>140), high-output HF, profuse sweating
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Is PTU or methimazole preferred for thyroid storm?
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PTU (b/c it blocks conversion of T3 to T4)
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What mesd are linked to thyroid problems?
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amiodarone
lithium |
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How do you treat euthyroid sick pt?
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trick question: will resolve on its own
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What effect does hypothyroidism have on the heart?
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reduces CO
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Which thyroid med has a higher ratio of T3:T4? (may cause T3 thyrotoxicosis)
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Armour thyroid
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What are the 4 most common causes of hyperthyroidism?
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Graves
Toxic multinodular goiter Autonomous nodule Thyroiditis |
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What will hyperthyroidism do to the heart?
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inc CO
inc myocardial oxygen demand in HR palpitations hyperdynamic precordium inc contractility etc |
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What drugs are used to tx hyperthyroidism?
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beta blockers
thionamides steroids cholestyramine |
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Which drug has a higher intrathyroidal concentration, methimazole or PTU?
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methimazole
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Which lasts longer, methimazole or PTU?
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methimazole
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What enzyme converts thyroine (T4) to triiodothyronine (T3) in extrathyroidal tissue?
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5'-monodeiodinase
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Which is more likely to cause an ANCA positive vasculitis, methimazole or PTU?
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PTU
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Which steroid is most often used for short term symptomatic tx of hyperthyroidism?
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dexamethasone
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Why is cholestyramine used for hyperthyroidism?
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inhibits enterohepatic recycling of thyroid hormone
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What restrictions are there before radioactive iodine for hyperthyroid?
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must be off T3 for 2 weeks and T4 for 4 weeks
no IV contrast in 2-3mo (get a urine iodine level) |
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How long does it take for radioactive iodine to work?
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2-12 weeks
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Surgery is often last choice for hyperthyroidism but is first choice for these three things. . .
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goiters
autonomous nodules thyroid CA |
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When is thyroiditis common?
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post-partum
following viral illness |
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How is thyroiditis treated?
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analgesics
time may offer beta blocker |
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do you treat thyroiditis with methimazole or PTU?
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neither!
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in thyroiditis which will normalize first, the FT4 or TSH?
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FT4
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What thyroid nodules are suggestive of CA?
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>1cm
microcalcifications inc vascularity |
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What is the most common thyroid CA?
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papillary
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TSH goal post papillary CA is ______, for medullary CA is ______
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0-0.5 (suppressed for papillary)
"normal" (for medullary) |
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Does amiodarone cause hypo or hyperthyroidism more often?
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hyper
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What drug can cause hyperthyroidism resistant to tx?
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amiodarone
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There is 10x as much iodine in this daily drug than in a nL diet.
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amiodarone
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