MCQs on Other Endocrine Disorders

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

Question 1

Which one of the following tests is most likely to differentiate hypercalcemia caused by hyperparathyroidism and cancer?

A) PTH.
B) Calcium level.
C) Phosphate.
D) Alkaline phosphatase.
E) Vitamin D level.

Correct Answer: A) PTH.

Explanation:
Primary hyperparathyroidism and malignancy are the two most common causes of hypercalcemia, with hyperparathyroidism being more common. Differentiating these causes clinically can be challenging in some cases, especially when presentations are atypical.

Measurement of intact parathyroid hormone (PTH) levels is the most reliable test to distinguish between the two:

In primary hyperparathyroidism, PTH levels are elevated or high-normal despite hypercalcemia.
In hypercalcemia of malignancy, PTH levels are typically suppressed or undetectable because the hypercalcemia is PTH-independent.

Other tests like serum calcium, phosphate, alkaline phosphatase, or vitamin D levels do not reliably differentiate these causes.

Rarely, a patient may have both malignancy and primary hyperparathyroidism, or a PTH-secreting tumor, which can complicate interpretation.

Question 2

A previously healthy and fit 35-year-old man presents with recent-onset palpitations and feeling edgy. On examination, he looks anxious. His blood pressure is 160/80 mmHg and heart rate 102 bpm. The rest of the exam is inconclusive. Which one of the following could be the most likely diagnosis?

A) Pheochromocytoma
B) Panic attack
C) Anxiety
D) Hyperthyroidism
E) Carcinoid syndrome

Correct Answer: D) Hyperthyroidism

Explanation:

Pheochromocytoma (A) typically presents with episodic spells of headache, palpitations, diaphoresis, and hypertension. The absence of episodic nature or headache and sweating makes pheochromocytoma less likely here.
Panic attack (B) usually involves acute, recurrent episodes lasting 20-30 minutes, with intense anxiety and somatic symptoms during attacks. There is no mention of episodic attacks or acute panic state on exam.
Anxiety disorder (C) often involves worry and palpitations but usually does not cause sustained hypertension; hypertension here is less typical.
Carcinoid syndrome (E) generally presents with flushing, diarrhea, and wheezing, which are absent in this patient, making it least likely.
Hyperthyroidism (D) commonly presents with nervousness, palpitations, elevated systolic blood pressure, and anxiety. The sustained hypertension and palpitations with anxiety symptoms fit best with hyperthyroidism.

Thus, hyperthyroidism is the most likely diagnosis given this clinical picture.

Question 3

A 38-year-old lady presents to your practice with fatigue, lethargy, and weight gain of 5 kg over the past few months. She also has irregular heavy periods. She feels flushed and tremulous. She is hypertensive, and her blood sugar is 10 mmol/L. Which one of the following is the most appropriate choice of investigation?

A) Thyroid function tests.
B) 24-hour urine cortisol level.
C) Serum FSH and LH.
D) Serum FSH and estradiol.
E) Serum prolactin level.

Correct Answer: B) 24-hour urine cortisol level.

Explanation:
This patient presents with clinical features suggestive of Cushing’s syndrome, which can include:

Weight gain
Fatigue and lethargy
Menstrual irregularities
Hypertension
Hyperglycemia
Tremulousness and flushing
Thin, easily bruised skin and purple striae may also be present.

Initial screening for Cushing’s syndrome is typically done with an overnight dexamethasone suppression test. If cortisol levels are not suppressed, further testing with a high-dose dexamethasone suppression test and 24-hour urine cortisol level measurement is performed for definitive diagnosis.

Other options like thyroid function tests, serum FSH, LH, estradiol, or prolactin are less likely to explain the full constellation of her symptoms and signs.

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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