A 45-year-old man presents with severe headache and hypertension (). Renal angiography demonstrates alternating areas of stenosis and aneurysmal dilation ('string of beads' appearance) in the right renal artery. What is the primary hormonal mechanism sustaining his hypertension?

Answer and explanation

Correct answer: D. Renal hypoperfusion activates juxtaglomerular renin release

  1. Step 1: Recognize fibromuscular dysplasia from the classic 'string of beads' angiographic appearance causing unilateral renal artery stenosis and secondary renovascular hypertension.
  2. Step 2: Narrowing of the renal artery decreases renal perfusion pressure at the afferent arteriole, which triggers granular juxtaglomerular cells to secrete renin. Renin converts angiotensinogen to angiotensin I, which is cleaved by ACE to angiotensin II, causing potent vasoconstriction and stimulating adrenal aldosterone secretion for sodium retention.
Answer
Renal hypoperfusion activates juxtaglomerular renin release.
Why not the others: Excessive secretion of epinephrine from a pheochromocytoma causes episodic paroxysmal headaches, diaphoresis, and palpitations without the 'string of beads' vascular lesion; Autonomous mineralocorticoid secretion by an adrenal adenoma describes primary hyperaldosteronism (Conn syndrome), which suppresses renin rather than activating it; Suppression of atrial natriuretic peptide (ANP) gene expression is not the initiating or sustaining endocrine driver in renovascular hypertension.

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