Renal Artery Stenosis

Question 1

Define renal artery stenosis

Answer 1

Narrowing of the renal artery

Question 2

What are the causes/risk factors of renal artery stenosis?

Answer 2

Atherosclerosis – 90%
• Diabetes
• Dyslipidaemia
• Smoking

Fibromuscular dysplasia – 10%
• Smoking
• Neurofibromatosis
• Takayasu’s arteritis
• Renal artery aneurysm
• Thromboemboli

Question 3

What are the symptoms of renal artery stenosis?

Answer 3

Recurrent flash pulmonary oedema

• Sudden SOB

Question 4

What are the signs of renal artery stenosis?

Answer 4

• Hypertension

* Renal artery bruit

Question 5

What investigations are carried out for renal artery stenosis?

Answer 5

• FBC - normal
• U&Es - hypokalaemia or low-normal potassium may suggest RAS due to activation of the renin-angiotensin system.
- eGFR may be normal or low in CKD.
• Urinalysis - RAS is not associated with proteinuria or abnormalities in the urinary sediment.
• Aldosterone-to-Renin Ratio - Aldosterone-to-renin ratio <20 excludes primary aldosteronism as cause of hypertension and hypokalaemia or low-normal potassium.
• Duplex USS - >50% Reduction in vessel diameter.
- Can also be seen in a CT Angiogram or MRA.
*Digital subtraction angiography is the gold standard for diagnosis.
• Renal Scintigraphy - uses the radio-agent 99Tc-DTPA (excreted by glomerular filtration) or 99Tc -MAG3 (excreted by tubules). Addition of an ACE inhibitor (captopril renography) causes delayed clearance by the affected kidney (may not be helpful if bilateral RAS).