Thyroid Pharmacology

THY-001 • Question 1

A 32-year-old woman has Graves disease (suppressed TSH, elevated free T4) with palpitations and tremor. Which medication provides the fastest symptomatic relief?

Methimazole Propranolol Radioactive iodine (I-131) Levothyroxine Potassium iodide solution

THY-002 • Question 2

Which enzyme is inhibited by thionamides (methimazole, PTU) in the thyroid gland?

Na+/K+ ATPase Thyroid peroxidase 5-alpha reductase Aromatase Dihydrofolate reductase

THY-003 • Question 3

Which statement best distinguishes PTU from methimazole?

PTU is preferred in the 1st trimester of pregnancy PTU causes more agranulocytosis than methimazole PTU is the drug of choice for chronic outpatient Graves maintenance PTU increases peripheral conversion of T4 to T3 PTU is contraindicated in thyroid storm

THY-004 • Question 4

A patient starts methimazole and develops fever and sore throat. Most appropriate next step?

Reassure; this is expected Order a CBC to evaluate for agranulocytosis Add levothyroxine to prevent hypothyroidism Stop propranolol immediately Give potassium iodide and continue methimazole

THY-005 • Question 5

Thyroid storm treatment sequencing: Which should be given BEFORE iodine (SSKI/Lugol) to avoid worsening hormone synthesis/release?

Methimazole or PTU Levothyroxine Liothyronine Radioactive iodine Cholestyramine only

THY-006 • Question 6

Which thyroid medication blocks peripheral conversion of T4 to T3 in addition to reducing synthesis?

Levothyroxine Liothyronine Propylthiouracil (PTU) Radioactive iodine Potassium iodide

THY-007 • Question 7

A 45-year-old with primary hypothyroidism is started on levothyroxine. Best counseling point to optimize absorption?

Take with a high-fat breakfast Take at bedtime with calcium Take on an empty stomach; separate from iron/calcium Take with grapefruit juice Take only when symptomatic

THY-008 • Question 8

Which lab is the best single test to monitor levothyroxine replacement in primary hypothyroidism (non-pregnant)?

Total T3 Free T4 only TSH Reverse T3 Thyroid stimulating immunoglobulin (TSI)

THY-009 • Question 9

A pregnant patient with Graves disease needs antithyroid therapy. Best choice during the 1st trimester?

Methimazole PTU Radioactive iodine High-dose levothyroxine No treatment is recommended

THY-010 • Question 10

Which therapy is CONTRAINDICATED in pregnancy and breastfeeding due to fetal/neonatal thyroid ablation?

Propranolol Methimazole Propylthiouracil (PTU) Radioactive iodine (I-131) Glucocorticoids

THY-011 • Question 11

High-dose iodine (SSKI/Lugol) helps severe hyperthyroidism primarily by:

Stimulating thyroid peroxidase Blocking thyroid hormone release (acute Wolff–Chaikoff effect) Increasing peripheral T4→T3 conversion Destroying thyroid tissue via radiation Blocking TSH receptors

THY-012 • Question 12

A patient with severe thyrotoxicosis is hospitalized and treated with a beta-blocker, thionamide, iodine, and steroids. Why are glucocorticoids used?

They increase TSH to normalize thyroid axis They block peripheral conversion of T4 to T3 and treat relative adrenal insufficiency They directly destroy thyroid follicles They increase renal excretion of T3 They prevent agranulocytosis from thionamides

THY-013 • Question 13

A 70-year-old with long-standing untreated hypothyroidism presents with hypothermia, bradycardia, and altered mental status. Most appropriate initial therapy?

Oral levothyroxine only IV levothyroxine ± IV liothyronine plus stress-dose hydrocortisone Radioactive iodine Methimazole High-dose iodine

THY-014 • Question 14

Which medication can cause hypothyroidism by inhibiting thyroid hormone release and also can cause hyperthyroidism (type 1 or type 2) due to iodine load and thyroiditis?

Amiodarone Hydrochlorothiazide Metformin Warfarin Digoxin

THY-015 • Question 15

Lithium is most associated with which thyroid adverse effect?

Hyperthyroidism due to TSH receptor stimulation Hypothyroidism due to impaired hormone release Thyroid cancer Pheochromocytoma Acromegaly