What a renal artery ultrasound shows
Each kidney is fed by an artery branching off the aorta. When one of those arteries narrows, the kidney reads the reduced flow as low blood pressure and signals the body to raise it. The result is hypertension that resists medication — and, over time, kidney function that slips away.
The study measures flow velocity in each renal artery and compares it with the aorta, and looks at the pattern of the waveform inside the kidney itself. It also measures kidney size, which tells us whether a kidney has already shrunk from long-standing poor flow.
What causes it
Two different diseases in two different populations. Atherosclerotic disease belongs to older patients with plaque elsewhere. Fibromuscular dysplasia belongs mostly to younger women, and is often missed for years. Renal Artery Stenosis / FMD →
Who should have one
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Blood pressure that stays high on three or more medications, one of them a diuretic
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Blood pressure that becomes hard to control abruptly, after years of being easy
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New hypertension before roughly age 30, or after roughly age 55
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Kidney function that worsens after starting an ACE inhibitor or ARB
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A kidney that is measurably smaller than the other, or unexplained flash pulmonary edema
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An abdominal bruit, or known atherosclerosis elsewhere Chronic Kidney Disease →
Finding a narrowing does not automatically mean opening it. Many are best treated medically, and revascularization is reserved for specific situations. What the ultrasound buys you is knowing.
For referring providers — Renal artery duplex is performed in our office with no contrast — which matters when the kidney in question is already compromised. Refer: (918) 943-5303 · fax (855) 312-3594.
Refer urgently: flash pulmonary edema, or a rapid decline in renal function after ACE-inhibitor or ARB initiation · Routinely: resistant hypertension, early- or late-onset hypertension, asymmetric kidney size, or an abdominal bruit. Full referral guide →