USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Renal artery stenosis can lead to secondary hypertension, and one of the most common causes is atherosclerosis. This condition typically affects older individuals, particularly those with a history of cardiovascular risk factors such as hypertension, diabetes, and hyperlipidemia. In atherosclerosis, plaques form in the renal arteries, narrowing them and impairing blood flow to the kidneys. The kidneys respond to this reduced perfusion by releasing renin, which activates the renin-angiotensin-aldosterone system (RAAS). Increased levels of angiotensin II lead to vasoconstriction and sodium retention, both of which contribute to elevated blood pressure.

In contrast, fibromuscular dysplasia, while also a possible cause of renal artery stenosis, is more common in younger women. It tends to present differently compared to atherosclerosis and has distinct characteristics, such as a "string of beads" appearance on imaging. Pulmonary embolism primarily affects the lungs and does not contribute to renal artery stenosis. Emphysema is a chronic lung condition that impacts the respiratory system and does not affect renal artery integrity or function. Thus, atherosclerosis stands out as a prevalent cause of renal artery stenosis and the resultant hypertension in the