Thyroid diseases MCQs With Answer

As B. Pharm students preparing for pharmacology and therapeutics exams, mastering Thyroid diseases MCQs With Answer is essential for clinical pharmacy practice. This concise, keyword-rich introduction covers hypothyroidism, hyperthyroidism, thyroiditis, Graves’ disease, thyroid function tests (TSH, T3, T4), antithyroid drugs (methimazole, PTU), levothyroxine therapy, radioactive iodine, and emergency management of thyroid storm and myxedema coma. Expect questions on mechanisms of action, pharmacokinetics, adverse effects like agranulocytosis and hepatotoxicity, drug interactions (e.g., amiodarone, calcium), and dosing in pregnancy. Clear understanding of diagnosis, treatment guidelines, and monitoring will boost exam performance. ‘Now let’s test your knowledge with 50 MCQs on this topic.’

Q1. Which laboratory test is considered the most sensitive single screening test for primary thyroid dysfunction?

• Serum free T3
• Serum free T4
• Serum thyroid-stimulating hormone (TSH)
• Thyroid peroxidase antibody (anti-TPO)

Correct Answer: Serum thyroid-stimulating hormone (TSH)

Q2. In primary hypothyroidism, the typical pattern of thyroid function tests is:

• Low TSH, low T4
• High TSH, low T4
• Normal TSH, low T4
• High TSH, high T4

Correct Answer: High TSH, low T4

Q3. Which antibody is most strongly associated with Graves’ disease and stimulates the thyroid gland?

• Anti-thyroid peroxidase (anti-TPO) antibody
• Thyroglobulin antibody
• TSH receptor-stimulating antibody (TSI or TRAb)
• Anti-mitochondrial antibody

Correct Answer: TSH receptor-stimulating antibody (TSI or TRAb)

Q4. Methimazole primarily exerts its antithyroid effect by:

• Blocking peripheral conversion of T4 to T3
• Inhibiting thyroid peroxidase and intrathyroidal iodination/coupling
• Competing with iodine for uptake into the thyroid
• Destroying thyroid follicular cells via radiation

Correct Answer: Inhibiting thyroid peroxidase and intrathyroidal iodination/coupling

Q5. Which antithyroid drug is preferred in the first trimester of pregnancy due to lower teratogenic risk?

• Methimazole
• Propylthiouracil (PTU)
• Carbimazole
• Radioactive iodine (I-131)

Correct Answer: Propylthiouracil (PTU)

Q6. A major idiosyncratic adverse effect of thionamides (methimazole and PTU) that requires immediate drug cessation is:

• Liver enzyme elevation only
• Agranulocytosis with fever and sore throat
• Hypokalemia
• Hyperglycemia

Correct Answer: Agranulocytosis with fever and sore throat

Q7. Which medication reduces peripheral conversion of T4 to T3 and is useful in thyroid storm management?

• Propranolol
• Levothyroxine
• Metformin
• Amiodarone

Correct Answer: Propranolol

Q8. The Wolff–Chaikoff effect explains the short-term response of the thyroid to large doses of iodine by:

• Increasing thyroid hormone synthesis
• Decreasing hormone synthesis via autoregulatory inhibition
• Stimulating TSH release from the pituitary
• Promoting thyroid hormone receptor activation

Correct Answer: Decreasing hormone synthesis via autoregulatory inhibition

Q9. Radioactive iodine (I-131) therapy is contraindicated in which situation?

• Graves’ disease in nonpregnant adults
• Multinodular toxic goiter in older adults
• Pregnancy and breastfeeding
• Persistent hyperthyroidism after surgery

Correct Answer: Pregnancy and breastfeeding

Q10. Which of the following best describes subclinical hypothyroidism?

• High TSH with low free T4 and severe symptoms
• Normal TSH with low free T4
• High TSH with normal free T4 and minimal or no symptoms
• Low TSH with normal free T4

Correct Answer: High TSH with normal free T4 and minimal or no symptoms

Q11. Levothyroxine therapy is usually monitored by measuring which parameter to adjust dose?

• Serum free T3
• Serum calcium
• Serum TSH
• Thyroglobulin

Correct Answer: Serum TSH

Q12. Which property of levothyroxine influences once-daily dosing and prolonged steady state?

• Short half-life (~24 hours)
• Long half-life (~7 days) and peripheral reservoir
• Rapid renal clearance
• Extensive first-pass hepatic metabolism causing variability

Correct Answer: Long half-life (~7 days) and peripheral reservoir

Q13. In elderly patients or those with ischemic heart disease, initial levothyroxine dosing should be:

• Full replacement dose (1.6 mcg/kg/day)
• Higher than usual to normalize TSH quickly
• Lower starting dose with gradual titration
• Given only at bedtime

Correct Answer: Lower starting dose with gradual titration

Q14. Which drug is a synthetic T3 preparation often used when rapid correction is needed or for myxedema coma?

• Levothyroxine (T4)
• Liothyronine (T3)
• Methimazole
• Calcitonin

Correct Answer: Liothyronine (T3)

Q15. Amiodarone-induced thyroid dysfunction may present as:

• Hypothyroidism only due to iodine excess
• Hyperthyroidism only due to iodine content
• Either hypothyroidism (type II) or hyperthyroidism (type I)
• No effect on thyroid function

Correct Answer: Either hypothyroidism (type II) or hyperthyroidism (type I)

Q16. Which thyroid disorder is most associated with anti-thyroid peroxidase (anti-TPO) antibodies and lymphocytic infiltration?

• Graves’ disease
• Hashimoto’s thyroiditis
• Subacute de Quervain’s thyroiditis
• Medullary thyroid carcinoma

Correct Answer: Hashimoto’s thyroiditis

Q17. A patient with hyperthyroidism scheduled for thyroidectomy should receive which preoperative medications to reduce thyroid vascularity and hormone release?

• High-dose levothyroxine
• Beta-blocker and potassium iodide (Lugol’s solution)
• Only methimazole withhold on day of surgery
• Radioactive iodine immediately before surgery

Correct Answer: Beta-blocker and potassium iodide (Lugol’s solution)

Q18. Thyroid storm management includes all EXCEPT:

• High-dose antithyroid drugs (PTU or methimazole)
• Beta-blockers to control adrenergic symptoms
• Immediate levothyroxine replacement with high doses
• Glucocorticoids to reduce T4→T3 conversion

Correct Answer: Immediate levothyroxine replacement with high doses

Q19. Which imaging finding is classically seen in Graves’ disease on thyroid scintigraphy (radioactive iodine uptake)?

• Low uptake diffusely
• High, diffuse uptake
• Single “cold” nodule
• Heterogeneous uptake with “hot” nodules only

Correct Answer: High, diffuse uptake

Q20. A “cold” nodule on thyroid scan indicates:

• Functioning tissue with increased hormone synthesis
• Non-functioning tissue that may be benign or malignant
• Diffuse Graves’ disease
• Subacute thyroiditis

Correct Answer: Non-functioning tissue that may be benign or malignant

Q21. Which lipid change is commonly associated with untreated hypothyroidism?

• Decreased LDL cholesterol
• Elevated LDL cholesterol and hypertriglyceridemia
• No change in lipid profile
• Markedly decreased HDL only

Correct Answer: Elevated LDL cholesterol and hypertriglyceridemia

Q22. In central (secondary) hypothyroidism due to pituitary failure, the expected lab pattern is:

• High TSH, low T4
• Low or inappropriately normal TSH, low T4
• High TSH, high T4
• Normal TSH, normal T4

Correct Answer: Low or inappropriately normal TSH, low T4

Q23. Which of the following drugs can decrease levothyroxine absorption when co-administered and requires spacing of doses?

• Amoxicillin
• Calcium carbonate supplements
• Acetaminophen
• Metformin

Correct Answer: Calcium carbonate supplements

Q24. Which clinical sign is most suggestive of hyperthyroidism?

• Bradycardia
• Cold intolerance and weight gain
• Tremor, heat intolerance, and weight loss
• Paresthesias and muscle weakness only

Correct Answer: Tremor, heat intolerance, and weight loss

Q25. Primary therapy for toxic multinodular goiter in an elderly patient who is a poor surgical candidate is often:

• High-dose levothyroxine suppression therapy
• Methimazole for life-long control
• Radioactive iodine ablation
• No treatment is indicated

Correct Answer: Radioactive iodine ablation

Q26. Which thyroid cancer is derived from parafollicular C cells and often secretes calcitonin?

• Papillary carcinoma
• Follicular carcinoma
• Medullary carcinoma
• Anaplastic carcinoma

Correct Answer: Medullary carcinoma

Q27. Which mutation is commonly associated with familial medullary thyroid carcinoma and MEN2 syndromes?

• BRAF V600E
• RET proto-oncogene mutation
• p53 mutation
• PTEN mutation

Correct Answer: RET proto-oncogene mutation

Q28. Lithium therapy can cause which thyroid abnormality?

• Thyroid hormone hypersecretion leading to hyperthyroidism
• Hypothyroidism due to reduced thyroid hormone release
• Immediate thyroid storm
• No effect on thyroid function

Correct Answer: Hypothyroidism due to reduced thyroid hormone release

Q29. The most appropriate initial management for subacute (painful) thyroiditis with thyrotoxic symptoms is:

• Immediate radioactive iodine
• High-dose methimazole indefinitely
• NSAIDs and beta-blockers; corticosteroids if severe
• Levothyroxine replacement

Correct Answer: NSAIDs and beta-blockers; corticosteroids if severe

Q30. Which feature differentiates myxedema coma from routine hypothyroidism?

• Mild fatigue and constipation
• Severe hypothermia, altered mental status, and hypotension
• Palpitations and tremor
• Isolated weight gain only

Correct Answer: Severe hypothermia, altered mental status, and hypotension

Q31. In the context of thyroid pharmacology, PTU has an advantage over methimazole because it:

• Is safer in long-term use due to less hepatotoxicity
• Inhibits peripheral conversion of T4 to T3 in addition to blocking thyroid peroxidase
• Has no risk of agranulocytosis
• Is rapidly cleared and therefore requires multiple daily doses

Correct Answer: Inhibits peripheral conversion of T4 to T3 in addition to blocking thyroid peroxidase

Q32. Which of the following indicates a therapeutic effect of radioactive iodine therapy for hyperthyroidism over weeks to months?

• Immediate decrease in serum TSH within hours
• Gradual decrease in thyroid hormone levels and eventual hypothyroidism
• Permanent stimulation of thyroid hormone synthesis
• Increase in thyroid vascularity

Correct Answer: Gradual decrease in thyroid hormone levels and eventual hypothyroidism

Q33. Which statement about thyroid hormone action at the cellular level is correct?

• T3 binds intracellular nuclear receptors and modulates gene transcription more potently than T4
• T4 is the only biologically active form and acts at the cell membrane
• Thyroid hormones act exclusively through G-protein coupled receptors
• T3 is inactive until converted into T4 in peripheral tissues

Correct Answer: T3 binds intracellular nuclear receptors and modulates gene transcription more potently than T4

Q34. Which of the following is a common lab pattern in subacute (de Quervain) thyroiditis during the initial phase?

• High TSH and low T4
• Low TSH and high T4 with elevated ESR
• Normal TSH and T4 with low ESR
• High TSH and high T4

Correct Answer: Low TSH and high T4 with elevated ESR

Q35. Which drug interaction is important to monitor in a patient starting levothyroxine while on warfarin therapy?

• Levothyroxine decreases warfarin effect reducing INR
• Levothyroxine increases warfarin response increasing INR and bleeding risk
• No interaction between levothyroxine and warfarin
• Levothyroxine causes vitamin K deficiency counteracting warfarin

Correct Answer: Levothyroxine increases warfarin response increasing INR and bleeding risk

Q36. Which clinical factor typically necessitates a higher replacement dose of levothyroxine?

• Elderly age over 75 years
• Pregnancy due to increased thyroid-binding globulin and demand
• Concomitant use of calcium supplements
• Recent bariatric surgery with malabsorption

Correct Answer: Pregnancy due to increased thyroid-binding globulin and demand

Q37. Which thyroid pathology is most likely when fine-needle aspiration cytology shows Orphan Annie eye nuclei and psammoma bodies?

• Follicular carcinoma
• Medullary carcinoma
• Papillary thyroid carcinoma
• Anaplastic carcinoma

Correct Answer: Papillary thyroid carcinoma

Q38. Which of the following is TRUE regarding thyroid hormone replacement and cardiovascular disease?

• Aggressive rapid normalization of TSH is safe in ischemic heart disease
• Excess thyroid hormone replacement can precipitate atrial fibrillation and ischemia
• Thyroid hormone has no effect on heart rate or contractility
• Levothyroxine reduces myocardial oxygen demand

Correct Answer: Excess thyroid hormone replacement can precipitate atrial fibrillation and ischemia

Q39. A patient on amiodarone develops hyperthyroidism with low radioiodine uptake and destructive thyroiditis picture; the likely mechanism is:

• Iodine-induced increased hormone synthesis (type I)
• Destructive thyroiditis causing release of preformed hormone (type II)
• Autoimmune stimulation by TRAb
• Prolonged TSH stimulation by pituitary adenoma

Correct Answer: Destructive thyroiditis causing release of preformed hormone (type II)

Q40. Which preventive strategy reduces the risk of methimazole-associated teratogenic effects during early pregnancy?

• Use methimazole in first trimester only
• Switch to propylthiouracil (PTU) during the first trimester
• Avoid all antithyroid drugs; use radioactive iodine during pregnancy
• Use high-dose iodine to block fetal thyroid development

Correct Answer: Switch to propylthiouracil (PTU) during the first trimester

Q41. Which diagnostic marker is most useful for detecting recurrent or residual differentiated thyroid cancer after thyroidectomy?

• Serum calcitonin
• Serum thyroglobulin (after TSH suppression/removal of thyroid tissue)
• Anti-TPO antibody
• Serum TSH only

Correct Answer: Serum thyroglobulin (after TSH suppression/removal of thyroid tissue)

Q42. Euthyroid sick syndrome (non-thyroidal illness) is characterized by which typical lab finding?

• Low T3 with normal T4 and TSH during acute illness
• High T3 and high T4 due to stress
• Persistently elevated TSH with normal hormones
• High T4 and suppressed TSH only

Correct Answer: Low T3 with normal T4 and TSH during acute illness

Q43. Which clinical feature is characteristic of Graves’ ophthalmopathy and may require specialized therapy?

• Proptosis (exophthalmos) and periorbital edema
• Binocular vision improvement with thyroxine
• Isolated eyelid ptosis without proptosis
• Reduced lacrimation only

Correct Answer: Proptosis (exophthalmos) and periorbital edema

Q44. Which medication may be used preoperatively to control heart rate and reduce peripheral T4→T3 conversion in severe thyrotoxicosis?

• Metformin
• Propranolol
• Furosemide
• Spironolactone

Correct Answer: Propranolol

Q45. Which statement regarding use of iodine-containing contrast or amiodarone before radioactive iodine therapy is correct?

• Recent iodine load increases RAI uptake and efficacy
• Iodine load reduces RAI uptake; waiting period is required before RAI therapy
• Amiodarone has no effect on RAI therapy timing
• Contrast agents permanently enhance thyroid imaging

Correct Answer: Iodine load reduces RAI uptake; waiting period is required before RAI therapy

Q46. Which of the following medications is most likely to cause agranulocytosis as a rare but serious adverse effect requiring CBC monitoring when symptomatic?

• Levothyroxine
• Methimazole
• Propranolol
• Calcium carbonate

Correct Answer: Methimazole

Q47. In postpartum thyroiditis, the typical course often follows which pattern?

• Permanent hyperthyroidism only
• Transient hyperthyroid phase followed by transient hypothyroid phase and recovery
• Immediate need for lifelong levothyroxine therapy
• No symptomatic phases; only antibody elevation

Correct Answer: Transient hyperthyroid phase followed by transient hypothyroid phase and recovery

Q48. Which management is most appropriate for a pregnant woman with uncontrolled hyperthyroidism who refuses surgery?

• Radioactive iodine therapy during second trimester
• Use propylthiouracil in first trimester then consider switching to methimazole
• No treatment is necessary during pregnancy
• High-dose levothyroxine to block TSH

Correct Answer: Use propylthiouracil in first trimester then consider switching to methimazole

Q49. Which of the following pharmacokinetic characteristics is true for liothyronine (T3) compared to levothyroxine (T4)?

• T3 has a longer half-life and slower onset
• T3 has a shorter half-life, more rapid onset, and greater potency per mcg
• T3 is inactive until converted to T4 in tissues
• T3 has identical dosing to levothyroxine by weight

Correct Answer: T3 has a shorter half-life, more rapid onset, and greater potency per mcg

Q50. Which monitoring parameter is most important after definitive radioactive iodine treatment for hyperthyroidism?

• Regular measurement of serum calcium
• Periodic assessment of TSH and free T4 to detect hypothyroidism
• Thyroid ultrasound every month indefinitely
• No follow-up is necessary after RAI

Correct Answer: Periodic assessment of TSH and free T4 to detect hypothyroidism

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