Endocrinology: adrenal medulla and catecholamine excess: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Endocrinology: adrenal medulla and catecholamine excess

Sample item

A 40-year-old woman with episodic headache, sweating and palpitations has paroxysmal hypertension, raised urinary metanephrines and an adrenal mass. A beta-blocker given alone before any other drug is followed by a severe rise in blood pressure. Why?

ABeta blockade increases renin release and angiotensin II formationBBlocked vascular beta-2 vasodilation leaves unopposed alpha-1 vasoconstrictionCBeta blockade raises tyrosine hydroxylase activity and synthesisDBeta blockade triggers further catecholamine release from the tumour

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Blocked vascular beta-2 vasodilation leaves unopposed alpha-1 vasoconstriction

Circulating catecholamines act on both alpha-1 receptors, which constrict vessels, and beta-2 receptors, which dilate vessels in muscle. Blocking beta receptors first removes the vasodilator effect, so alpha-1 vasoconstriction is unopposed and blood pressure can surge. Alpha blockade is therefore started before a beta-blocker.

Option by option

A. Beta blockade increases renin release and angiotensin II formation
Beta-1 blockade reduces renin release from the juxtaglomerular cells, so this would lower, not raise, pressure.
B. Blocked vascular beta-2 vasodilation leaves unopposed alpha-1 vasoconstriction (correct)
Correct. Loss of beta-2 mediated vasodilation leaves alpha-1 vasoconstriction unopposed.
C. Beta blockade raises tyrosine hydroxylase activity and synthesis
Beta blockade does not up-regulate tyrosine hydroxylase, the rate-limiting enzyme of synthesis.
D. Beta blockade triggers further catecholamine release from the tumour
The tumour releases catecholamines independently, and beta blockade does not provoke more release.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is B, Blocked vascular beta-2 vasodilation leaves unopposed alpha-1 vasoconstriction. Circulating catecholamines act on both alpha-1 receptors, which constrict vessels, and beta-2 receptors, which dilate vessels in muscle.

Why is "Beta blockade increases renin release and angiotensin II formation" not the answer?

Beta-1 blockade reduces renin release from the juxtaglomerular cells, so this would lower, not raise, pressure.

Why is "Beta blockade raises tyrosine hydroxylase activity and synthesis" not the answer?

Beta blockade does not up-regulate tyrosine hydroxylase, the rate-limiting enzyme of synthesis.

Why is "Beta blockade triggers further catecholamine release from the tumour" not the answer?

The tumour releases catecholamines independently, and beta blockade does not provoke more release.

What concept does this question test?

It tests Endocrinology: adrenal medulla and catecholamine excess in Physiology. Blocking beta receptors first removes the vasodilator effect, so alpha-1 vasoconstriction is unopposed and blood pressure can surge. Alpha blockade is therefore started before a beta-blocker.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Endocrinology: adrenal medulla and catecholamine excess?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.