Term
| what is a protein that binds >99% of thyroid hor in plasma? what are 2 other proteins that transport hormones in blood? |
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Definition
| thyroid-binding globulin (tbg). also, thyroid-binding pre-albumin (tbpa), and albumin |
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Term
| where is t4 converted to t3? |
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Definition
| in cells. t3 activates nuclear receptors, followed by increase in rna and protein synthesis |
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Term
| Who should be screened for hypothyroidism? |
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Definition
| all newborns, all adults every 5 yrs starting at age 35 |
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Term
| Does amiodarone cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does thyroiditis cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does ectopic thyroid tissue cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does exogenous thyroid hormone cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does iodinated radiocontrast dye cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does grave's dz cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does tsh-secreting tumors cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does pituitary resistance to t4 cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Do trophoblastic dz cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does a toxic adenoma cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
| Does a multinodal goiter cause increased or decreased raiu (radioactive iodine uptake)? |
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Definition
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Term
50 y/o woman with 15 lb weight loss
c/o insomnia, muscle weakness, leg swelling, dysphagia, eyes “stick out”
PE: HR 100 bpm, mild proptosis, enlarged thyroid gland, 2+ pitting edema.
TSH < 0.02 mIU/mL and T4 18.2 mcg/dL
What drug, dose, schedule, and duration of therapy is most appropriate to treat this patient?
What parameters would you monitor to evaluate efficacy and safety? |
|
Definition
Antithyroid Medications
Thionamides
Propylthiouracil (PTU)
Methimazole
Iodides
Radioactive iodine (RAI)
Surgery (subtotal thyroidectomy)
Adjunctive Pharmacotherapy
beta-blockers |
|
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Term
| What is the moa of methimazole (tapazole)? |
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Definition
blocks organification of iodides and inhibits coupling of MIT and DIT ->
Decreases thyroid hormone production |
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Term
| What are the 2 thionamides and what do they tx? |
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Definition
| ptu, methimazole (tapazole), hyperthyroidism |
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Term
| What is the moa of Propylthiouracil (PTU)? |
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Definition
blocks organification of iodides and inhibits coupling of MIT and DIT.
Also inhibits peripheral T4 to T3 conversion |
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Term
| What is the drug of choice in pregnancy/lactation, thyroid storm? |
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Definition
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Term
| Pt on ptu develops agranulocytosis, aplastic anemia, arthralgias, lupus-like syndrome, and hepatotoxicity. Should you switch to methimazole? |
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Definition
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Term
| The following are major s/e of what drug class: aplastic anemia, arthralgias, lupus-like syndrome, and hepatotoxicity. |
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Definition
| thionamides. agranulocytosis is also a major s/e. |
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Term
| agranulocytosis is associated w/what drug class? |
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Definition
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Term
| Pt on ptu develops pruritic maculopapular rash, arthralgias, fever, benign transient leukopenia. Should you try methimazole? |
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Definition
| may try other agent, cross sensitivity ~50% |
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Term
| The following are s/e of what drug class: pruritic maculopapular rash, arthralgias, fever, benign transient leukopenia? |
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Definition
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Term
| how long does it take to normalize ft4 and tsh levels after administration of thionamides? when should you re-run ft4 levels? |
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Definition
Symptoms and hormone levels normalize in 4-8 weeks.
Monitor FT4 4-6 weeks after initiation of therapy and after dose changes.
FT4 normalizes after 4-8 weeks but TSH may remain suppressed for several months after euthyroid |
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Term
| once a pt is euthyroid, how frequently do you reassess tft's? |
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Definition
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Term
| what are 3 labs you run when starting a pt on thionamides? |
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Definition
| baseline ft4, tsh, and cbc w/diff |
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Term
| what is the remission rate w/thionamides? |
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Definition
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Term
| what are 2 iodine tx for hyperthyroidism? |
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Definition
| Lugol’s solution (6 mg/drop) or saturated potassium iodide solution (SSKI, 38 mg/drop) |
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Term
| what is the moa for iodine? |
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Definition
| MOA: acutely blocks thyroid hormone release, inhibits thyroid hormone synthesis, decreases gland vascularity |
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Term
| hsn rxns, burning mouth, gi upset, and gynecomastia are ade of what drug? |
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Definition
| iodine. iodism is metallic taste, burning mouth, gi upset |
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Term
| what is Used pre-operatively before thyroid surgery or after RAI treatment? |
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Definition
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Term
| what drug can be used for people exposed to radiation? What are the 2 fda-approved products? |
|
Definition
Potassium iodide competitively inhibits uptake of radioactive iodine. thyro-block, losat. Risk of developing thyroid cancer after exposure to radioactive iodine is greatest in neonates, infants, and small children.
The risk is smallest in adults > 40 years old |
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Term
| What is now the most common t of hyperthyroidism? |
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Definition
|
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Term
|
Definition
| MOA: incorporated into thyroid hormones and thyroglobulin leading to follicular necrosis |
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Term
| what is the major ade of rai? |
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Definition
|
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Term
| what is often required w/rai? |
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Definition
| Often requires concomitant antithyroid/adjunctive agents |
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Term
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Definition
| Remission: 60% within 6 months, another 40% in 1 yr with additional doses |
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Term
| what is the moa of beta-blockers? |
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Definition
| MOA: block beta-adrenergic receptors and partially block conversion of T4 to T3 to ameliorate thyrotoxic symptoms |
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Term
| what is an adjunctive tx for hyperthyroidism? |
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Definition
| beta-blockers (commonly propranolol) |
|
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Term
| when is propranolol contraindicated? |
|
Definition
| Contraindicated with CHF, bradycardia, caution with asthma, COPD, DM |
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Term
What is a Life threatening medical emergency with
Severe thyrotoxicosis, high fever, tachycardia, tachypnea, dehydration, delirium N/V/D that is
Precipitated by infection, trauma, surgery, RAI, withdrawal of antithyroid meds? how is it tx? |
|
Definition
thyroid storm. Treatment includes:
PTU, iodides, propranolol, corticosteroids, and supportive measures |
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Term
BR is a healthy, 65 y/o woman without complaints
Elevated TSH (6-7.5 mIU/ml), normal T3, FT4
What thyroid disorder does this patient have? Potential risks involved?
Is thyroid hormone replacement indicated? |
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Definition
|
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Term
| what is the drug of choice for hypothyroidism? |
|
Definition
| Levothyroxine (Synthroid, Levoxyl, Unithroid, etc.) |
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Term
| is Levothyroxine (Synthroid, Levoxyl, Unithroid, etc.) t3 or t4? |
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Definition
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Term
What initial dose of levothyroxine would you recommend for a 55 y/o, 75 kg male with a PMH of GERD, HTN, hyperlipidemia and angina?
A) 25 mcg daily
B) 50 mcg daily
C) 0.050 mg daily
D) 100 mcg daily
E) 125 mcg daily |
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Definition
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Term
| What are 3 enzyme inducers that cause Increase in thyroid hormone? |
|
Definition
Rifampin
Carbamazepine
Phenytoin |
|
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Term
| what are 4 substances that cause Impaired absorption of thyroid hormone? |
|
Definition
| Iron, antacids, calcium, and sucralfate |
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Term
| what drug causes Inhibition of conversion from T4 to T3? |
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Definition
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Term
What is a Synthetic T3 that is
Used diagnostically for T3 suppression test and has a
t ½ ~1.5 days with the following
Disadvantages: cost, increased cardiac adverse effects, monitoring? |
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Definition
|
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Term
| What is a synthetic t4:t3 in a 4:1 ratio? |
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Definition
Liotrix (Thyrolar, Euthyroid).
Predictable potency, expensive, ? therapeutic rationale – majority of studies show no benefit over levothyroxine |
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Term
what is Derived from hog, beef or sheep thyroid glands and has a
Variable ratio of T4 and T3? |
|
Definition
thyroid usp (armour and generic). Inexpensive, unpredictable hormonal stability, antigenic.
Rarely used except in older, stable patients who won’t switch to a newer product |
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Term
| how do dose requirements for hpothyroidism meds change w/age and pregnancy? |
|
Definition
Dose requirements increase in pregnancy; monitor TSH every trimester.
Dose requirements may decrease with age |
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|
Term
55 y/o, 70 kg female with HTN
c/o weight gain, fatigue, constipation, cold hands/feet
PE: dry skin, coarse hair
Meds: lisinopril, HCTZ, ASA, Maalox prn (~6x/wk)
Labs: TSH 12.6 mIU/mL, FT4 0.7 ng/dL
What drug therapy would you recommend? Initial dose?
Dosing instructions/counseling points?
What lab parameter would you monitor for efficacy? When? |
|
Definition
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|
Term
what is End stage of uncontrolled, long-standing hypothyroidism with
Advanced hypothyroid symptoms, hypothermia, delirium, and coma? How do you tx? |
|
Definition
myxedema coma. Needs aggressive treatment with IV thyroxine, glucocorticoids, and supportive measures.
Levothyroxine 400-500 mcg IV x 1;
300 mcg if cardiac disease,
Then 50-100 mcg/day IV.
Improvement of symptoms within 24 hrs.
Switch to oral levothyroxine once the patient is stable |
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