The most common cause of renovascular hypertension in younger patients is which condition?

• A. Atherosclerosis
• B. Fibromuscular dysplasia
• C. Pheochromocytoma
• D. Coarctation

Answer: (B)

Renovascular hypertension in younger patients is most often due to fibromuscular dysplasia, a non-atherosclerotic, non-inflammatory disease that causes narrowing of the renal arteries. When the renal blood supply drops, the kidney releases renin, activating the renin-angiotensin-aldosterone system and raising blood pressure. This condition is especially common in young individuals, particularly women, making it the leading cause of renovascular HTN in that age group.

Imaging classically shows a string-of-beads pattern on renal artery angiography from alternating stenosis and small aneurysmal dilations caused by medial fibroplasia. Clinically, patients may have resistant hypertension that improves after renal angioplasty.

The other conditions have different mechanisms or demographic patterns. Atherosclerosis tends to cause renal artery stenosis in older patients with generalized vascular disease. Pheochromocytoma produces episodic hypertension with headaches, sweating, and tachycardia rather than a primary renovascular cause. Coarctation of the aorta raises upper-body blood pressure via a distinct aortic narrowing, not primarily through renal artery stenosis.