AIM • KMU Exam Practice

Question:

A 34-year-old woman has weight loss, tremor and persistent palpitations. Serum TSH is markedly suppressed and free T4 is within the upper normal range. Clinical suspicion of hyperthyroidism remains high. Which additional laboratory finding would best explain the presentation?

Options:

Correct Answer: Elevated circulating T3

Explanation: Some patients develop T3-predominant thyrotoxicosis, in which TSH is suppressed and T3 is elevated despite a less striking free T4 result.

Question:

A 29-year-old woman with untreated Graves disease has a diffusely enlarged thyroid. During examination, a bruit is heard over the gland. Which pathological change best explains this finding?

Options:

Correct Answer: Marked increase in thyroid vascularity

Explanation: Persistent stimulation in Graves disease produces a highly active and vascular gland, allowing turbulent blood flow to be heard as a thyroid bruit.

Question:

A thyroid biopsy from a woman with autoimmune hyperthyroidism shows diffuse follicular epithelial hyperplasia. Which additional microscopic finding would further support the autoimmune nature of the disease?

Options:

Correct Answer: Lymphoid follicles with germinal centres

Explanation: Lymphocytes and lymphoid follicles with germinal centres may occur in Graves disease and reflect its underlying autoimmune pathogenesis.

Question:

Microscopy of a hyperfunctioning thyroid shows tall follicular cells surrounding pale colloid with irregular scalloped margins. What best explains the altered appearance of the colloid?

Options:

Correct Answer: Accelerated uptake of stored colloid by active follicular cells

Explanation: The hyperactive follicular cells rapidly resorb colloid for hormone release, producing the characteristic scalloped appearance seen in Graves disease.

Question:

A 46-year-old man with untreated hyperthyroidism reports difficulty rising from a chair and climbing stairs. Examination shows proximal muscle weakness without focal neurological deficit. Which mechanism best explains this finding?

Options:

Correct Answer: Increased protein turnover and catabolism

Explanation: Excess thyroid hormone accelerates protein turnover and catabolism, which can produce characteristic proximal muscle weakness in hyperthyroidism.

Question:

Two patients have biochemical thyrotoxicosis. Both show lid retraction, but only one has proptosis and restricted ocular movements. Which mechanism best explains the lid retraction that may occur in either patient?

Options:

Correct Answer: Increased sympathetic activity

Explanation: Lid retraction and lid lag can result from increased adrenergic activity in thyrotoxicosis, whereas true Graves ophthalmopathy is an autoimmune orbital process.

Question:

A 63-year-old woman has long-standing nodular thyroid enlargement, recent weight loss and palpitations. TSH is suppressed and thyroid scintigraphy shows multiple irregular areas of increased activity separated by relatively suppressed tissue. Which diagnosis best fits this pattern?

Options:

Correct Answer: Toxic multinodular goitre

Explanation: Multiple autonomously functioning nodules produce the characteristic irregular or patchy uptake pattern of toxic multinodular goitre.

Question:

A 52-year-old woman has confirmed biochemical hyperthyroidism. Examination reveals an irregular nodular thyroid rather than diffuse enlargement. Which investigation is most useful for characterizing the structural abnormalities of the gland?

Options:

Correct Answer: Thyroid ultrasonography

Explanation: Ultrasound is particularly useful for defining nodules and other structural thyroid abnormalities after biochemical hyperthyroidism has been established.

Question:

A patient with Graves disease is prescribed carbimazole. During a pharmacology discussion, the student is asked how this drug relates to another commonly used thioamide. Which statement is correct?

Options:

Correct Answer: It is converted into methimazole

Explanation: Carbimazole is a prodrug that is converted to methimazole, which then inhibits thyroid peroxidase and reduces new hormone synthesis.

Question:

A woman receiving methimazole for Graves disease develops jaundice and biochemical evidence of cholestatic liver injury. Which interpretation is most appropriate?

Options:

Correct Answer: The finding is a recognized methimazole adverse effect

Explanation: Methimazole can cause cholestatic hepatic injury, whereas severe hepatotoxicity is an especially important concern with propylthiouracil.

Question:

A woman with Graves hyperthyroidism presents during early pregnancy and requires antithyroid medication. Which pharmacological consideration most strongly favors avoiding methimazole during this stage?

Options:

Correct Answer: It has characteristic early fetal teratogenic risks

Explanation: Methimazole exposure during early fetal development has recognized teratogenic risks, which influences thioamide selection during early pregnancy.

Question:

A patient with marked thyrotoxicosis receives propranolol for cardiovascular and neurological symptoms. In addition to β-adrenergic blockade, which action can contribute to its usefulness?

Options:

Correct Answer: Reduction of peripheral T4-to-T3 conversion

Explanation: Propranolol primarily controls adrenergic symptoms and can additionally reduce peripheral conversion of T4 to the more active T3.

Question:

A patient with severe thyrotoxicosis receives a large pharmacological dose of iodide after a thioamide has been started. Which paired effect best reflects the acute thyroid response to the iodide load?

Options:

Correct Answer: Reduced organification and reduced hormone release

Explanation: A large iodide load acutely suppresses thyroid-hormone organification and release, producing rapid but temporary inhibition of thyroid activity.

Question:

A breastfeeding woman with persistent Graves hyperthyroidism is discussing definitive treatment. Which option is inappropriate because the administered agent may expose thyroid tissue in the nursing infant?

Options:

Correct Answer: Radioactive iodine therapy

Explanation: Radioactive iodine is contraindicated during breastfeeding because radioiodine exposure can affect thyroid tissue in the nursing infant.

Question:

A patient receives iodine-131 for persistent hyperthyroidism. The treatment is effective because one thyroid cell type preferentially concentrates iodine before radiation causes local tissue damage. Which cell is the principal therapeutic target?

Options:

Correct Answer: Thyroid follicular cell

Explanation: Follicular cells actively concentrate iodine for thyroid-hormone synthesis, allowing iodine-131 to deliver targeted radiation to functioning thyroid tissue.

Question:

A 51-year-old woman has persistent hyperthyroidism with a markedly enlarged thyroid causing pressure symptoms in the neck. She requires definitive treatment. Which management principle is most appropriate?

Options:

Correct Answer: Assessment for thyroidectomy

Explanation: A substantial goitre producing compressive symptoms is an important situation in which surgical definitive treatment may be preferable.

Question:

A patient with Graves disease becomes euthyroid after a course of medical antithyroid therapy. During counseling about prognosis, which statement is most appropriate?

Options:

Correct Answer: Hyperthyroidism can recur after medical treatment is stopped

Explanation: Thioamides suppress hormone synthesis but do not remove thyroid tissue, so recurrence of Graves hyperthyroidism can occur after a medical treatment course.

Question:

A 37-year-old woman with Graves disease has mild proptosis, dry gritty eyes and no visual loss, colour-vision disturbance or significant restriction of ocular movements. Which management principle is most appropriate at this stage?

Options:

Correct Answer: Ocular-surface protection and lubrication

Explanation: Mild Graves ophthalmopathy without sight-threatening features can be managed initially with supportive measures that protect and lubricate the exposed ocular surface.

Question:

A woman with Graves disease develops progressive orbital discomfort, conjunctival chemosis and diplopia. Visual acuity and colour vision remain preserved. The ophthalmopathy is considered clinically active. Which management principle is most appropriate?

Options:

Correct Answer: Specialist assessment for anti-inflammatory therapy

Explanation: Active inflammatory Graves ophthalmopathy may require specialist-directed anti-inflammatory or immunomodulatory treatment according to severity.

Question:

A 35-year-old woman with diffuse autoimmune hyperthyroidism has bilateral proptosis and develops localized thickening of the skin over the anterior shins. Which explanation best links the skin finding with her underlying disease?

Options:

Correct Answer: Localized autoimmune connective-tissue involvement

Explanation: Pretibial myxedema is an extrathyroidal manifestation of Graves disease produced by autoimmune connective-tissue changes rather than by direct excess thyroid-hormone action.