Health condition
Adrenal venous sampling
Adrenal venous sampling (AVS) is the key test in primary aldosteronism that determines whether one adrenal gland or both are overproducing aldosterone - the answer decides between curative surgery and lifelong medication.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.
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A catheter passed from the groin samples blood directly from each adrenal vein
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Needed because CT appearances are unreliable - a visible nodule is not always the culprit gland
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Lateralised results point to keyhole adrenalectomy with a real prospect of cure
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Technically demanding: success rates depend heavily on the radiologist's experience, so centre choice matters
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Usually done as a day case with cortisol-corrected measurements to verify catheter placement
Understanding the condition
What it is and what happens next.
What causes it, how it is diagnosed, and the treatment routes available in the UK.
What it is and how it feels
In primary aldosteronism the crucial question is geography: a single adenoma can be removed, curing or dramatically improving the condition, while bilateral overactivity needs medication instead. CT cannot settle this - harmless nodules are common with age, and tiny functioning adenomas can be invisible - so removing a gland on scan appearance alone risks the wrong operation. AVS answers it by measuring aldosterone from each adrenal vein directly.
Diagnosis and treatment routes
The procedure takes an experienced interventional radiologist: the right adrenal vein is notoriously difficult to cannulate, and success rates range widely between centres, so it is fair to ask how many your hospital performs. Results are interpreted with cortisol correction by the endocrine team, and a clearly lateralised result opens the door to laparoscopic adrenalectomy. If AVS has been recommended but the wait is long, specialist private pathways exist; an initial private endocrinology review is typically available within about two weeks.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a consultant endocrinologist and interventional radiologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.
Frequently asked
Common questions about Adrenal venous sampling.
Quick, plain-English answers to what people ask us most.
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What is adrenal venous sampling?
Adrenal venous sampling is a specialised diagnostic procedure that involves taking blood samples directly from the veins draining each adrenal gland to determine whether one or both glands are producing excess aldosterone, most often used in evaluating primary aldosteronism (Conn's syndrome).
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Why is adrenal venous sampling needed?
It helps distinguish whether excess aldosterone is coming from one adrenal gland (suggesting a tumour that could be surgically removed) or both glands equally (suggesting a condition better treated with medication), which imaging alone often cannot reliably determine.
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Is adrenal venous sampling a risky procedure?
It is a specialised, minimally invasive procedure performed by experienced interventional radiologists, generally safe, though it carries a small risk of bleeding, bruising, or, rarely, adrenal vein injury.
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How is adrenal venous sampling performed?
A thin catheter is guided through a vein, usually in the groin, up to each adrenal vein under X-ray guidance, with blood samples taken from each side and compared with samples from a peripheral vein.
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How long does adrenal venous sampling take and what is recovery like?
The procedure itself typically takes one to two hours, with most patients able to go home the same day or after a short observation period, and normal activities resumed within a day or two.
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What happens after adrenal venous sampling?
Results guide treatment decisions: if excess aldosterone is confirmed from one side, surgical removal of that adrenal gland may be recommended; if both sides are involved, medication is usually the preferred treatment.
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Adrenal venous sampling vs CT/MRI imaging alone — what's the difference?
Imaging can show the physical appearance of the adrenal glands but cannot always reliably determine which gland is functionally overactive, whereas adrenal venous sampling directly measures hormone levels from each gland, providing more accurate functional information for treatment planning.
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Is adrenal venous sampling always necessary before adrenal surgery?
It is generally recommended before surgery for suspected primary aldosteronism, particularly when imaging is inconclusive or shows subtle or bilateral changes, to avoid removing the wrong or an unnecessary gland.
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Is adrenal venous sampling technically difficult?
Yes, it is a technically demanding procedure requiring specialist expertise, and success rates in correctly sampling both adrenal veins vary between centres, so it is best performed at experienced specialist units.
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When should I discuss adrenal venous sampling, and how quickly can I be seen privately?
Discuss this with your endocrinologist if primary aldosteronism is suspected. NHS referral to a specialist centre can take several weeks to months, while private specialist assessment is often available within about two weeks.