Endocrine Medicine 12 Single Best Answer (SBA)

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Electrolyte & Endocrine SBA Quiz

1. A 25-year-old man presents with bilateral breast enlargement over the past 6 months. He denies pain or nipple discharge. Examination confirms glandular tissue without signs of malignancy. He is on spironolactone for hypertension. What is the most appropriate next step?

  • Discontinue spironolactone and consider alternative antihypertensive
  • Reassure the patient and review in 6 months
  • Refer for surgical excision
  • Perform a mammogram and biopsy

Answer: Discontinue spironolactone and consider alternative antihypertensive

Spironolactone-induced gynaecomastia often improves after switching to an alternative antihypertensive. Further investigations are warranted only if symptoms persist or worsen.

2. A 30-year-old woman presents with bilateral milky nipple discharge. She denies breast pain or masses. Prolactin levels are elevated. What is the most likely underlying cause?

  • Prolactinoma
  • Breast cancer
  • Hypothyroidism
  • Idiopathic hyperprolactinaemia

Answer: Prolactinoma

In a patient with galactorrhoea and high prolactin, a prolactin-secreting pituitary adenoma (prolactinoma) is often the culprit.

3. What is the primary underlying mechanism of lactose intolerance?

  • Autoimmune destruction of intestinal lactase
  • Genetic deficiency of lactase enzyme in the small intestine
  • Damage to intestinal villi from infection or inflammation
  • Congenital absence of lactose absorption pathways

Answer: Genetic deficiency of lactase enzyme in the small intestine

Primary (adult-onset) lactase deficiency is genetically determined and the most common cause of lactose intolerance.

4. A 55-year-old man with hypertension is found to have an incidental adrenal mass on imaging. Plasma aldosterone-renin ratio is elevated. What is the most likely diagnosis?

  • Phaeochromocytoma
  • Adrenal adenoma causing primary hyperaldosteronism
  • Adrenal carcinoma
  • Cushing’s syndrome

Answer: Adrenal adenoma causing primary hyperaldosteronism

A high aldosterone-renin ratio is characteristic of primary hyperaldosteronism, often due to an aldosterone-producing adrenal adenoma (Conn’s syndrome).

5. A 45-year-old woman presents with bitemporal hemianopia and persistent headaches. MRI reveals a 2 cm pituitary tumour. What is the next best step?

  • Measure prolactin, ACTH, and IGF-1 levels
  • Start bromocriptine therapy immediately
  • Refer for urgent surgical resection
  • Arrange radiotherapy

Answer: Measure prolactin, ACTH, and IGF-1 levels

A pituitary macroadenoma (≥1 cm) requires a thorough endocrine workup to determine if it is functioning (prolactinoma, acromegaly, Cushing’s disease, etc.) or non-functioning.

6. A 70-year-old man presents with confusion and serum sodium of 118 mmol/L. What is the most appropriate immediate management?

  • Administer IV hypertonic saline
  • Restrict oral water intake
  • Start oral sodium supplements
  • Prescribe demeclocycline

Answer: Administer IV hypertonic saline

Acute or severely symptomatic hyponatraemia with confusion or seizures warrants careful correction with IV hypertonic saline to prevent cerebral oedema.

7. What is the most serious complication of untreated hyperkalaemia?

  • Severe muscle weakness
  • Life-threatening cardiac arrhythmias
  • Acute kidney injury
  • Hypertension

Answer: Life-threatening cardiac arrhythmias

Hyperkalaemia disrupts cardiac conduction, risking dangerous arrhythmias and cardiac arrest if not promptly corrected.

8. Which medication is most commonly associated with hypokalaemia?

  • Spironolactone
  • Furosemide
  • Metformin
  • Propranolol

Answer: Furosemide

Loop diuretics (e.g., furosemide) promote potassium excretion in the renal tubules, making them a common cause of hypokalaemia.

9. A 60-year-old man with post-thyroidectomy hypocalcaemia presents with tetany and a positive Chvostek’s sign. What is the most appropriate immediate treatment?

  • IV calcium gluconate
  • Oral calcium and vitamin D supplements
  • Start bisphosphonates
  • Monitor and repeat serum calcium in 24 hours

Answer: IV calcium gluconate

Acute hypocalcaemia with tetany requires IV calcium replacement to alleviate neuromuscular excitability.

10. A 75-year-old woman with metastatic breast cancer and hypercalcaemia refuses further treatment. She is confused and dehydrated. How should the healthcare team proceed?

  • Administer IV fluids and bisphosphonates without her consent
  • Respect her decision and provide supportive care only
  • Assess her capacity to refuse treatment
  • Refer to palliative care for decision-making

Answer: Assess her capacity to refuse treatment

If a patient with hypercalcaemia is confused, their capacity may be compromised. Capacity assessment is vital before respecting a refusal of care.

11. What is the most common complication of severe hypermagnesaemia?

  • Cardiac arrest
  • Hypertension
  • Seizures
  • Hyperreflexia

Answer: Cardiac arrest

Excess magnesium depresses neuromuscular and cardiac conduction, potentially causing cardiac arrest in severe cases.

12. What is the most common cause of hypernatraemia in the elderly?

  • Diabetes insipidus
  • Excessive sodium intake
  • Dehydration due to impaired thirst mechanism
  • Hyperaldosteronism

Answer: Dehydration due to impaired thirst mechanism

In older patients, diminished thirst response and inadequate fluid intake are key contributors to hypernatraemia.

Total Score: 0/12