Which feature best distinguishes essential hypertension from secondary hypertension due to renal artery stenosis?

Explanation

## Distinguishing Essential from Secondary Hypertension (Renal Artery Stenosis) ### Key Discriminating Feature **Key Point:** An abdominal systolic bruit (especially diastolic component) on auscultation is a classic sign of renal artery stenosis and is rarely present in uncomplicated essential hypertension. The bruit results from turbulent flow across a stenotic renal artery. ### Comparison Table | Feature | Essential HTN | Renal Artery Stenosis | |---------|---------------|----------------------| | **Abdominal bruit** | Absent | Present (systolic ± diastolic) | | **Serum creatinine** | Normal (early) | Often elevated (especially if bilateral) | | **LVH** | Common (chronic) | Common (chronic) | | **Nocturnal BP** | May be elevated | May be elevated | | **Age of onset** | Usually > 40 yrs | Can be any age; fibromuscular dysplasia in young women | | **Hypokalemia** | Rare | May occur (secondary hyperaldosteronism) | ### Clinical Pearl **Clinical Pearl:** While both conditions cause LVH and may have elevated creatinine, the **abdominal bruit is the most specific bedside finding** that points directly to renal artery stenosis. It is present in ~50% of hemodynamically significant stenosis cases and is virtually never heard in pure essential hypertension. ### High-Yield Point **High-Yield:** Remember the mnemonic for secondary hypertension clues: **"ABCDE"** - **A**bdominal bruit (RAS) - **B**oundary of kidney mass (polycystic kidney disease) - **C**oarctation murmur (aortic coarctation) - **D**iastolic murmur (aortic regurgitation from aortic dissection) - **E**ndocrine (pheochromocytoma, primary aldosteronism) ### Why Other Options Are Less Discriminating - **Elevated creatinine & reduced GFR:** Both can occur in essential HTN with chronic kidney disease progression; also seen in RAS but not specific to it. - **LVH on echo:** A consequence of prolonged hypertension regardless of cause; present in both conditions. - **Nocturnal BP elevation:** Occurs in both essential and secondary hypertension; not a discriminator. [cite:Harrison 21e Ch 297]