A catheter-based diagnostic test that pinpoints whether excess aldosterone driving high blood pressure is coming from one adrenal gland or both — guiding the choice between surgery and medication.
Primary aldosteronism occurs when one or both adrenal glands produce too much aldosterone, a hormone that regulates salt and blood pressure — causing high blood pressure that is often more severe or harder to control than typical hypertension, sometimes with low blood potassium. It's one of the most common identifiable, and treatable, causes of high blood pressure, yet is frequently under-recognised because its symptoms overlap with ordinary hypertension.
Once primary aldosteronism is confirmed with blood tests, the next question is where the excess hormone is coming from: a single, hormone-producing adenoma in one adrenal gland, or overactivity affecting both glands (bilateral adrenal hyperplasia). This distinction matters enormously, because the two are treated completely differently — but a CT or MRI scan alone frequently cannot answer it reliably. Small, incidental, non-functioning adrenal nodules are common in the general population and become more so with age, so a nodule seen on a scan doesn't necessarily prove that side is the source of the excess hormone, and a normal-looking gland doesn't rule it out either. AVS answers this question directly, by measuring hormone levels at the source rather than inferring it from anatomy alone.
Patients with confirmed primary aldosteronism being considered for adrenal surgery and otherwise fit for an operation.
Normal-appearing adrenal glands despite confirmed excess hormone, or nodules seen on both sides.
Most patients being evaluated for surgery, since current guidance recommends AVS before adrenalectomy in the majority of cases.
A single needle puncture is made in the femoral vein in the groin under local anaesthesia.
A thin catheter is guided in turn into the right and then left adrenal vein under X-ray guidance.
Blood is drawn from each adrenal vein and a peripheral vein, often before and after ACTH stimulation.
Most patients are observed briefly afterward and go home the same day.
Patients with confirmed primary aldosteronism who are being considered for adrenal surgery and are otherwise fit for an operation — since the entire purpose of AVS is to guide that decision.
Patients where imaging findings are ambiguous or don't fit the biochemical picture, such as normal-appearing adrenal glands despite confirmed excess hormone production, or nodules on both sides.
Most patients being evaluated for surgery, since current guidance recommends AVS before adrenalectomy in the majority of cases, given how often imaging alone would lead to the wrong conclusion.
A small subset of younger patients with a clear, classic biochemical and imaging picture may sometimes proceed toward surgery without AVS under specific guideline-based criteria — this is a judgment made jointly with the endocrinology team, not a default. AVS isn't useful for patients who aren't candidates for surgery or aren't considering it, since the result wouldn't change how their condition is managed.
Planning: a dedicated adrenal-protocol CT is reviewed beforehand to map the anatomy of the adrenal veins, particularly the right adrenal vein, which is short and variable in its origin from the inferior vena cava.
Access: under local anaesthesia, a single needle puncture is made in the femoral vein in the groin.
Catheterisation: a thin catheter is guided under X-ray guidance in turn into the right and then the left adrenal vein — the right side is the technically demanding step of the procedure, given its small calibre and variable anatomy.
Sampling: blood samples are drawn from each adrenal vein and from a peripheral vein for comparison, often before and after a hormone stimulation (ACTH) to improve accuracy and reduce variability caused by the stress of the procedure itself.
Confirming correct placement: cortisol levels measured at each sampling site confirm the catheter was truly in the adrenal vein rather than a nearby vessel, before the aldosterone results from that side can be trusted — a step called checking selectivity.
Recovery: most patients are observed for a short period afterward and go home the same day.
Once selective sampling is confirmed on both sides, the aldosterone level (adjusted against the cortisol level at the same site, to account for dilution) is compared between the right adrenal vein, the left adrenal vein, and the peripheral blood sample. A clear excess from one side relative to the other indicates a unilateral, surgically treatable source; similar, elevated levels from both sides point to bilateral disease, better managed with medication. These results are reviewed jointly with the endocrinology team alongside the patient's biochemical and imaging findings before a final treatment decision is made.
The right adrenal vein is one of the technically hardest structures in the body to cannulate reliably — short, narrow, and variable in exactly where it joins the inferior vena cava — and success rates for achieving selective sampling on both sides vary meaningfully with operator experience. Because the entire value of the test depends on the catheter genuinely being in the adrenal vein when each sample is drawn, a misplaced catheter doesn't just fail to help — it can actively mislead the treatment decision toward surgery on the wrong side or away from surgery altogether. AVS is best performed in centres doing the procedure regularly, working in close coordination with the endocrinology team managing the patient's diagnosis and treatment.
AVS is used to find out whether excess aldosterone hormone, causing high blood pressure, is coming from one adrenal gland or both, in patients diagnosed with primary aldosteronism — the answer determines whether surgery or medication is the right treatment.
Small, non-functioning adrenal nodules are common, especially with age, so a nodule seen on a scan doesn't prove it's the hormone-producing one, and a normal-looking gland doesn't rule out disease there either. AVS measures hormone levels directly at the source instead of relying on how the gland looks on imaging.
The procedure is done under local anaesthesia through a single groin puncture, so it isn't painful at the time. Most patients are observed for a short period afterward and go home the same day, with a brief period of reduced activity while the puncture site heals.
That depends on the result. A clearly one-sided source usually means surgical removal of the affected adrenal gland is a realistic, often highly effective option. A two-sided source is generally treated with medication instead, since surgery wouldn't address the gland left behind.
AVS is generally very safe, with a low rate of complications related to the puncture site or catheter. The greater technical challenge is achieving accurate, selective sampling — particularly on the right side — which is why it's best performed by an interventional radiologist experienced specifically in this procedure.
Book a consultation with Dr. Giragani, or send your reports for a specialist second opinion.