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102 Cards in this Set
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- Back
- 3rd side (hint)
What is the functional unit of the thyroid |
Follicle wall |
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What is thyroglobulin? |
Glycoprotein containing over 100 Tyr residues Where TH is synthesized and stored |
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The thyroid is regulated by ___ |
1) HPT axis -TH and ACTH provide negative feedback 2) TSH -regulates and controls synth and release of TH from follicles -multiple effects on TH, other hormones, thyroid gland, other tissue |
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How is TH synthesized |
synth stim by TSH 1) I transferred into gland from blood via transporters RLS 2)TGn expression INC 3) I and TGn secreted into colloid -I oxidized to I+ or converted to I2 by thyroperoxidase as ar the 2 Tyr residues of TGn (MIT and DIT) 4) Tyr's are coupled in colloid(synthesis) -t3 -t4 -TGn+t4+t3 "droplets" (storage) |
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How is TH secreted? |
Endocytosis of TGn droplets containing T3 and T4 Enzymatic TGn cleavage releases T4 T4 released into the blood |
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What are TH actions |
1)Regulates overall metabolic activity and energy expenditure -receptors on nucleus, mitochondria,membranes Brain is exception 2)Growth and development(very important for FETUS GROWTH and DEVELOPMENT) 3)Inc activity of adrenergic nervous sys 4)Inc GI motility 5)Inhibit TRF, TSH (- feedback) |
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In what ways does TH regulate metabolic activity and energy expenditure? |
1) inc basal metabolic rate 2)inc protein synth and catabolism 3) inc carbohydrate metabolism Inc glycogen,gluconeogen Inc gi absorp, adipose & muscle uptake of glucose dec insulin action Hyperthyroidism exacerbates DM 4) increases lipid and cholesterol metabolism -inc lipolysis -inc conversion of cholest to bile acids Due to inc LDL rec on hepatocytes Why hypothyroid have inc cholesterol |
4 main ways |
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How does th inc adrenergic NS activity |
Inc beta rec on heart skel musc adipose and lymphocytes Dec alpha rec in myocardial tissue Inx catechol sensitivity +inotropic +chronotropic |
4 ways |
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Hypothyroidism (Or Gull's Disease) is more common on ___ |
Older women ( 4-8x more likely in women) |
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Gull's disease is a ___ onset that tends to ____ |
Slow "Wax and wane" |
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Typical signs and symptoms of hypothyroidism are: |
-chronic fatigue,somnolence, expressionlessness -poor circulation -muscle cramps (dec muscle func) -faulty hearing -unexplained weight gain -decreased mental func and motor activity -cold, dry skin, hair loss -Hothermia/cold sensitivity -constipation -reproductive disorders - cardiac difficulties (dec CO, bradycardia, dec BP) -goiter (usually diffuse non toxic goiter) -myxedema |
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What is myxedema |
Severe hypothyroidism in which poor lymph drainage leads to SubQ buildup of mucopolysaccharides characterized by: -puffy hands and feet -swelling of cheeks and tongue -Puffy eyes and droopy eyelids - dec CV function, CO and glomerular filtration -NOT correctible with diuretics |
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What are lab values associated with hypothyroidism |
Hypercholesterolemia dec drug metab and elimination (higher drug half life) TSH levels |
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Types of PRIMARY hypothyroidism |
Hashimoto's thyroiditis (90%) Thyroidectomy of radioactive I tx Endemic(area w low I) Drug induced Cretinism Myxedemic coma |
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What is hashimotos thyroiditis |
Chronic autoimmune thyroiditis- autoantibodies attack thyroid causing damage and inflammation Most people have it Mean age diagnosis ~60 |
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What drugs can induce Hypothyroidism |
Amiodarone Iodine Lithium(5-15% in long term tx) |
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What drugs cause both hypo and hyperthyroidism |
Amiodarone and Lithium |
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What is cretinism |
Congenital hypothyroidism that can lead to irreversible mental and growth retardation |
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What are signs and symptoms of cretinism |
Thick tongue Dry,brittle hair Hypothermia: dry, cool skin Poor feeding Choking episodes Short extremities Goiter Overall inactive/ sluggish |
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What is a myxedemic coma |
Medical emergency with a 60% mortality rate and is associated with severe and chronic hypothyroidism |
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What are clinical features of myxedemic coma |
Profound hypothermia Unconsciousness delayed reflexes Respiratory depression Bradycardia Rough skin |
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What are precipitating factors of myxedemic coma |
Stress Infection Hypothermia |
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What are possible treatment options for myxedemic coma |
Liothyronine sodium (T3) injection -triostat, cytomel |
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What is a treatment option for endemic hypothyroidism |
Iodine |
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What are different TH replacement agents |
Levothyroxine (pure T4) Liothyronine sodium (T3) Thyroid USP (dessicated thyroid) (4/1 ratio 4/3) Liotrix (older) Thyroid strong (older) natural prep 1.5 more potent than thyroid USP |
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Levothyroxine has a ___ t1/2 and is ____ absorbed. |
Long Well (50-70%) |
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Brand interchange with levothyroxine is ___ |
Not recommended due to formulation differences |
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Levo should be taken when the stomach is ___ |
Empty |
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Levothyroxine drug interactions |
Fe Ca Al sucralfate, cholestyramine |
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What is the equivalent dose of levo |
100 ug |
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Liothryonine sodium has a ___ onset ___ duration and is ___ potent than T4 |
Rapid Shorter More |
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What is the equivalent dose for triostat |
25-30ug |
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What is the equivalent dose of thyroid USP |
About 65 mg (1 grain) |
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Hyperthyroidism (grave's disease) is ___ and is typically seen in ____ |
Not as common as hypo Young adults |
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What are some signs and symptoms of hyperthyroidism |
Exaggerated TH effects -elevated BMR -warm,nervous -weight loss -increased appetite -muscle weakness and hyperreflexia
Osteoporosis Inc RBC mass: inc menstrual flow Arrhythmias (tachycardia) Exopthalamus 1) TSH induced inflamm of connective tissue 2) ai reaction leads abies mimicking TSH wh activate TR leading to deposits in eye socket 3) eyelid retraction/ lag Goiter |
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Types of primary hyperthyroidism |
1)Graves disease (diffuse toxic goiter, exopthalmic goiter) 2)Nodular toxic goiter 3)drug induced |
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What is graves disease |
AI disorder that is the predominant cause of hyperthyroidism in which ANTIBODIES mimick TSH and overstimulate gland with no negative feedback loop |
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What are characteristics of graves disease |
Diffuse toxic goiter (entire gland enlarges and hypertrophies, high th leads to thyrotoxicosis) Exopthalmos Pretibia myxedema(thyroid dermapothy) Can "wax and wane" |
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What is a nodular toxic goiter |
Isolated nodes or groups of cells in the thyroid gland that become hyperactive and resistant to pit feedback regulation
Not the whole gland |
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Generally do NOT observe ___ with nodular toxic goiter |
Exopthalmos |
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A diffuse non toxic goiter is thought to be caused by |
Increased TSH due to higher T3 levels caused by I defecit? |
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Endemic goiters are caused by __ leading to ___ TH levels and ___ TSH levels |
I deficiency Decreased Increased |
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Treatment for a nodular toxic goiter is |
Surgery |
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Treatment for a diffuse non toxic goiter is |
Iodine |
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Treatment for a diffuse toxic goiter is |
Surgery Radioactivd I Drugs |
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Treatment for an endemic goiter is ___ |
Iodine |
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What drugs can induce hyperthyroidism |
Amiodarone Lithium |
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__ is essential for first trimester growth and development |
TH |
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Hyperthyroidism in pregnancy is usually caused by __ |
Graves disease |
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Thyrotoxicosis (excessive th levels) in pregnancy can cause |
Cv complications Preeclampsia Premature birth/ miscarriage Low birth weight Thyroid storm |
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What agents are available to treat hyperthyroidism |
Antithyroid agents Thioamides Iodines Radioactive iodine Surgery Beta blockers (propranolol) |
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Antithyroid agents are more successful in ____ |
Mild diffuse toxic goiter |
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Antithyroid agents are useful for ___ |
Young Adults and children |
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If using antithyroid agents in pregnancy___ because ____ |
Use lower doses Higher doses may induce hypothyroidism in fetus |
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Constant use and correct dosage are paramount with __ Bec d/ of therapy after one year results in relapse of up to ___% of patients |
Antithyroid agents 50 |
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What is the MOA of thioamides |
Inhibition of thyroperoxidase PTU- inhibits monodeiodination of T4 |
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What are the 2 thioamide agents in use today |
Methimazole (MTZ) Propylthiouracil (PTU) |
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What are advantages of using thioamides |
Causes no permanent damage Concentrates in thyroid Any hypo is reversible by lowering dose Refractiveness uncommon SE low- fever and rash |
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Disadvantages of using thioamides (MTZ and PTU) |
1-2 mth for effect (need to deplete t3/t4 stores) May cause goiter b/c of inc TSH due to depletion of stores Therapy is long and must be continual Not a cure and may not work with severe disease Pregnancy category D(mtz) Short T1/2 (PTU) |
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What is a serious side effect of thioamides |
Agranulocytosis PTU dose related? Look for fever, rapid developing sore throat Rapid onset |
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PTU is the DOC in___ |
1st trimester, thyroid storm |
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MTZ is DOC in all situations but __ |
1st trimester and thyroid storm |
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The effects of iodides on hyperthyroidism wear of in about___ |
2 months |
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At pharmacologic doses, iodides ___ |
Dec t4/3 synthesis and secretion Reduce vascularity of the thyroid gland |
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Iodides are used for__ |
Surgery prep Diffuse non toxic goiter Radiation emergency (nuclear stuff to prevent cancer) |
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What is the mechanism for radioactive I (RAI) |
I131 concentrates in the thyroid |
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Pros of using RAI |
Destroys thyroid tissue Simple convenient and permanent Works well for small nodular or diffuse toxic goiters Usually 2nd or 3rd line |
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Cons of using RAI |
3-4 weeks for onset and 4 mths to full effect Can be too effective and too permanent (cause HoThyroid) Crosses placenta and damages fetus so CI in pregnancy Occasional damage to parathyroids |
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RAI is used in |
ADULTS 30- 40 And refractory pts or pts hypersens to drugs |
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Surgery for hyperthyroidism is __ |
Useful for large nodular toxic goiters and always for malignancies Used in drug sensitivity or failure Only used in pregnancy if necessary All disadvant of surgery Occasional PTH damage VERY effective |
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What is thyroid storm |
Life threatening, exaggerated thyrotoxic manifestations usually seen in untreated, severe hypothyroidism |
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Symptoms of thyroid storm include: |
Agitation Confusion Diarrhea Restlessness, shaking Severe hyperthermia Sweating Tachycardia |
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What concurrent medical conditions can precipitate thyroid storm |
Infection CV distress Stress |
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Treatment of thyroid storm includes high doses of: |
Beta blockers Anti arrhythmics Antithyroid agents (PTU and iodides) Ice bath, ice packs, acetaminophen |
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Primary thyroid disease originates in___ |
Thyroid |
Allison |
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Secondary disease is caused by ___ |
TSH from pituitary |
jA |
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Tertiary disease is caused by___ |
TRH from hypothalamus |
Ja |
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Resin T3 uptake is |
An indirect measurement of the degree of saturation of thyroid binding globulin (TBG) It gives an INDIRECT estimate of free t4 avail for binding to TBG |
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FT4 I = ____ |
RT3U x TT4 |
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FT4 I compensates for ___ and is ___ expensive than measuring FT4 |
TBG Less |
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Normal TSH range is |
0.4 - 2.5 uU/mL |
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TSH is ___ in primary hypothyroidism |
Elevated |
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Iatrogenic hypothyroidism is ___ |
Caused by healthcare sys somehow Rai, surg, DI |
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Drug induced hypothyroidism caused by |
Nitroprusside Amiodarone Lithium Sulfonylureas(esp 1st gen) |
Ja |
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A TaRGET DOSE for levo can be set as: |
1.6 ug/kg/d |
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A senior citizen (>60) or anyone with a + h/o heart disease should be started on a much ___ dose because___ |
Lower Target dose could unmask a pre existing heart condition and precipitate angina |
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A senior citizen starting levo should be monitored for__ |
HoThyroid symptoms TSH Chest pain |
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Doses of levo should be readjusted every 6-8 weeks toward target dose with an end goal of ___ |
Normal tsh levels |
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TSH is __ in secondary hypothyroidism |
Low |
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What kind of effect does dessicated thyroid have on thyroid tests |
normal FT4/FT4I TSH normal or Inc TT3 |
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Couples having trouble conceiving should have ___ levels tested |
TSH |
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Hyperthyroidism etiology: ____ is autoimmune ____ toxic nodules ____ viral - also self limiting ____ |
Graves disease Plummer's disease Sub Acute Thyroiditis Drug induced |
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Monitoring for thioamides should include___ |
CBC with differential |
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_ is NOT an absolute CI for thioamides but _ is |
Rash Agranulocytosis |
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_ provide symptomatic relief before onset of thioamides use in thyroid storm and as a preop adjunct. |
Iodides |
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DONT USE _ before RAI |
Iodides |
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Adrenergic agents in hyperthyroidism ___ |
Block the peripheral action of TH but have no effect on disease state. |
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When it comes to adrenergic antagonists, ___ are preferred agents |
Beta blockers (propranolol) |
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Use__ in hyperthyroidism during pregnancy or lactation |
PTU and BB |
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Steroids like prednisone can be used to prevent worsening of ___ |
Exopthalmos |
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AFib with hyperthyroidism should be treated with additional meds like |
Beta blockers CCBs Digoxin |
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Thyroid storm treatment : |
Support with sedation O2 Fluids Thioamides Lugols solution30-60 gtt/d Bb (propranolol) CCB (diltiazem) |
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