Renovascular disease is the most common cause of 2° HTN in adults. Can be d/t ischemia from renal stenosis or microvascular disease. Can hear renal bruits lateral to umbilicus.

Main causes of renal artery stenosis:

• Atherosclerotic plaques—proximal 1/3rd of renal artery, usually in older males, smokers.

• Fibromuscular dysplasia—distal 2/3rd of renal artery or segmental branches, usually young or middle-aged females.

Lab values based off:

1. Stenosis decreases blood flow to glomerulus.
2. Juxtaglomerular apparatus (JGA) responds by secreting renin, which converts angiotensinogen to angiotensin I.
3. Angiotensin I is converted to angiotensin II (ATII) by angiotensin converting enzyme (ACE --in lungs)
4. ATII raises blood pressure by (1) contracting arteriolar smooth muscle, increasing total peripheral resistance and (2) promoting adrenal release of aldosterone, which increases reabsorption of sodium (where Na+ goes H2O will follow) in the distal convoluted tubule (expanding plasma volume). Can lead to hypokalemia (seen in the labs for this question)
5. Leads to HTN with increased plasma renin and unilateral atrophy (due to low blood flow) of the affected kidney; neither feature is seen in primary hypertension

The patient has a bruit which is turbulent blood flow due to something obstructing like stenosis causing renovascular HTN.

• if you measure just aldo, what are you expecting? You heard the bruit, you know there's probably stenosis so does a high aldo tell you the cause? Typically the non-invasive approach to assessing renovascular HTN is checking plasma renin.

• MR angiography can better explain if the bruit is the reason why the patient has renovascular HTN. We learned in my renal course, gold std is renal arteriography but you can use MRA.