MCQs on Adrenals – AMC Wise

Written by Dr. James Whitfield (MBBS, FRACGP) – General Practitioner

Question 1

Rebecca, a 35-year-old woman, presents with progressive weight gain, facial rounding, and purple striae on her abdomen over the past 6 months. She also complains of muscle weakness and irregular menstrual periods. On examination, she has central obesity, hypertension, and proximal muscle wasting. Laboratory tests reveal elevated 24-hour urinary free cortisol and failure to suppress serum cortisol after overnight dexamethasone suppression test.

Which of the following is the most appropriate next step to determine the cause of her Cushing’s syndrome?

A) Serum ACTH measurement
B) Abdominal ultrasound
C) MRI of the adrenal glands
D) Plasma renin activity
E) Serum aldosterone level

Correct Answer: A) Serum ACTH measurement

Explanation:
The diagnosis of Cushing’s syndrome is confirmed by elevated cortisol levels and lack of suppression on dexamethasone testing. The next step is to measure serum ACTH to differentiate between ACTH-dependent (e.g., pituitary adenoma) and ACTH-independent causes (e.g., adrenal adenoma).

Low or suppressed ACTH suggests an adrenal cause, whereas elevated or normal ACTH points to pituitary or ectopic ACTH secretion. Imaging studies follow ACTH measurement to localize the source.

Question 2

James, a 45-year-old man, is evaluated for persistent hypertension despite three antihypertensive medications. He reports muscle weakness and occasional cramps. Laboratory tests reveal hypokalaemia with serum potassium of 2.8 mmol/L. Plasma aldosterone concentration is elevated, and plasma renin activity is suppressed.

Which of the following is the most likely diagnosis?

A) Essential hypertension
B) Primary hyperaldosteronism
C) Pheochromocytoma
D) Cushing’s syndrome
E) Secondary hyperparathyroidism

Correct Answer: B) Primary hyperaldosteronism

Explanation:
Primary hyperaldosteronism results from autonomous overproduction of aldosterone, causing hypertension, hypokalaemia, and suppressed renin levels. It is an important and potentially curable cause of secondary hypertension.

Confirmatory tests include the aldosterone-renin ratio (ARR) and imaging to identify adrenal adenomas or hyperplasia. Other options are less consistent with hypokalaemia and suppressed renin.

Question 3

Emma, a 29-year-old woman, presents with fatigue, weight loss, dizziness on standing, and hyperpigmentation of her skin and oral mucosa. She reports salt craving and has had intermittent vomiting. Blood pressure is 90/60 mmHg, and orthostatic hypotension is noted. Laboratory tests show hyponatraemia, hyperkalaemia, and low serum cortisol. A short synacthen test reveals inadequate cortisol response.

Which of the following is the most likely diagnosis?

A) Secondary adrenal insufficiency
B) Addison’s disease
C) Cushing’s syndrome
D) Pheochromocytoma
E) Hypothyroidism

Correct Answer: B) Addison’s disease

Explanation:
Addison’s disease is primary adrenal insufficiency caused by autoimmune destruction or other damage to the adrenal cortex, leading to deficient production of cortisol, aldosterone, and adrenal androgens. Clinical features include fatigue, weight loss, hypotension, hyperpigmentation (due to increased ACTH stimulating melanocytes), and electrolyte disturbances like hyponatraemia and hyperkalaemia.

The short synacthen test (ACTH stimulation test) shows inadequate cortisol response confirming adrenal insufficiency. Differentiating from secondary adrenal insufficiency is important: secondary causes have low ACTH and lack hyperpigmentation and mineralocorticoid deficiency.

Management involves lifelong glucocorticoid and mineralocorticoid replacement, patient education on stress dosing, and monitoring for adrenal crisis.

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5. Endocrine Module

5.1 Diabetes

5.2 Thyroid

5.3 Breast

5.4 Adrenals

5.5 Osteoporosis

5.6 Other Endocrine Disorders

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