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BackTable / VI / Article
Adrenal Vein Sampling: Clinical Management Before & After
Rajat Mohanka • Feb 28, 2024 • 87 hits
The primary clinical indication for adrenal vein sampling is the definitive diagnosis of primary hyperaldosteronism. This diagnostic procedure plays a crucial role in determining the appropriate treatment pathway for patients, be it surgical intervention or medical management, contingent upon the identification of a dysfunctional adrenal gland. Effective communication with the endocrinologist is imperative, as it enhances patient comprehension of the procedure's clinical significance and implications for their treatment plan.
Dr. Fritz Angle, an interventional radiologist from University of Virginia, explains the clinical indications for adrenal vein sampling, how to medically manage patients before the procedure, and his post-procedure protocol. This article includes excerpts from the BackTable Podcast. The full episode is featured below.
The BackTable Brief
• Adrenal vein sampling is primarily used for diagnosing primary hyperaldosteronism in individuals with hypertension.
• It is essential to check the aldosterone-renin ratio, which should be above 20 to diagnose primary hyperaldosteronism.
• Interventional radiologists should work closely with endocrinologists and have access to surgeon colleagues should the need for an adrenalectomy arise.
• Compare aldosterone to cortisol ratios from the right and left adrenal glands to identify lateralization.
• Because potassium-sparing diuretics are suspended prior to the procedure, obtain a stat potassium level to adjust for hypokalemia to ensure patient safety.
• While IRs may sometimes be viewed strictly as procedural specialists, Dr. Fritz Angle emphasizes the significance of being invested in patient care through simple actions like follow-up calls.
Table of Contents
(1) Indications for Adrenal Vein Sampling
(2) Pre-Procedure Protocols for a Successful Adrenal Vein Sampling
(3) Post-Procedure Protocols for a Successful Adrenal Vein Sampling
Indications for Adrenal Vein Sampling
The primary application of adrenal vein sampling is to diagnose primary hyperaldosteronism, a notably under-diagnosed yet increasingly detected condition accounting for less than 5% of hypertension cases worldwide. Dr. Fritz Angle emphasizes the necessity of referrals from endocrinologists, though sometimes primary care doctors also make referrals. Crucial to the pre-procedure workup is the aldosterone-renin ratio, which should exceed 20 to confirm excess aldosterone production and suppressed renin levels. Dr. Angle advocates for an initial clinic visit to review essential lab work, medication lists, and possibly required imaging like CT scans, underscoring the frequency of unexpected findings during these consultations.
[Dr. Aparna Baheti]
Okay let's just get right into it. Adrenal vein sampling. What are some of the indications that you see for this procedure?
[Dr. Fritz Angle]
Almost every referral for adrenal vein sampling is patients have primary hyperaldosteronism, and this is a clinical diagnosis. Patients should come from an endocrinologist. Sometimes you'll get referred by primary care doctor. That's an important distinction, but that's pretty much the only indication is primary hyperaldosteronism.
[Dr. Aparna Baheti]
How common is that disease in the general population?
[Dr. Fritz Angle]
So we're seeing increasing numbers of this. I think finally we're starting to detect more of these. It accounts for less than 5% of hypertension, which doesn't sound like much, but there's a lot of hypertension out there. I mean, worldwide, there's probably a billion people walking around with hypertension. This is a well under-diagnosed disease.
[Dr. Aparna Baheti]
So walk me through your workup for these patients before you start the procedure on them.
[Dr. Fritz Angle]
The most important thing, the easiest thing for you to do is you just need to see the aldosterone-renin ratio, and that should be more than 20. The referring doctor should have figured that out before they send that to you. These people are making too much aldosterone, and it should suppress their renin. Sometimes the renin levels are undetectable, which means you have a very high ratio. If it's less than 20, you may want to send that patient back to that referring doctor for a little bit more in-depth analysis.
[Dr. Aparna Baheti]
Are these labs that you require prior to seeing them in the clinic?
[Dr. Fritz Angle]
That's exactly right. There's really not much I want to see before, but you need to know what their aldosterone and renin levels are, and beyond that, really just list of their medications, allergies, the usual things.
[Dr. Aparna Baheti]
Do you see all these patients for a pre-visit in your clinic?
[Dr. Fritz Angle]
I do. I highly recommend everyone do this. It's a simple procedure. You may say, "Why bring these people through clinic?" So often, there are surprises in the clinic, and usually, the lab work you're looking for isn't available or hasn't been done. CAT scan that you require hasn't been done, or you need to review the medications that are on that can interfere with the test.
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Pre-Procedure Protocols for a Successful Adrenal Vein Sampling
Patients are at risk for exacerbated hypokalemia when suspending potassium-sparing diuretics 2-6 weeks prior to the procedure. Therefore, patients should continue their usual potassium supplements and blood pressure medications on the procedure day to mitigate the risks of high blood pressure and low potassium levels. The use of CT scans, both non-contrast and with contrast, is recommended for locating the right adrenal vein and screening for adrenal nodules. On the day of the procedure, a stat potassium level is recommended to adjust for potential aldosterone gradient masking due to hypokalemia.
[Dr. Aparna Baheti]
I see. I know we have a list of medications you can look up online, but off the top of your head, can you tell our audience what meds you stop before the procedure and for how long?
[Dr. Fritz Angle]
I think the most important medication class is any of the potassium-sparing diuretics. Most people agree, although it remains a little controversial, that you need to hold those. Traditionally, we said they had to be held for six weeks, but I think there's more and more literature that maybe two weeks is enough. The reason that's important is all these patients, as you know, get into trouble with hypokalemia, and you stop their potassium-sparing diuretics, and it gets more severe…
[Dr. Aparna Baheti]
Got it. Once you've identified those medications and stopped them, are there any other pre-procedure instructions you provide to your patients in regards to this procedure?
[Dr. Fritz Angle]
A lot of these patients are on potassium supplements, oral supplements, and most are instructed not take it on empty stomach. I do try and have them take all their medications that morning of the procedure, whatever blood pressure medications they're on, whatever potassium supplements they are on, because when they get there, a lot of times they have really high blood pressure and really low potassium levels because they stopped their spironolactone.
[Dr. Aparna Baheti]
That's really good to know. I'd like to know a little bit about the CT scan that you get beforehand.
[Dr. Fritz Angle]
…Of course, all these patients should be screened for adrenal nodules many times. That's just a noncontrast CT, and I'm fine with that, but if I can, if they've not ordered a CT, then I'm going to order one with contrast, and often I can see pretty clearly where that adrenal vein joins the IVC, which speeds up the procedure...
[Dr. Aparna Baheti]
In researching for this, I read a little bit about the right adrenal vein and variant anatomy for the right adrenal vein, and I read that there was some controversy about whether the right adrenal vein can come off one of the hepatic veins. In your experience, is that something that you see?
[Dr. Fritz Angle]
Yes. The hardest part of the whole procedure is finding that right adrenal vein, and there are a lot of caudate lobe branches, small hepatic vein branches joining the IVC. You need to learn to differentiate, "Okay is this a hepatic vein I'm looking at, or is this the gland?" Then the second problem we have is that sometimes that adrenal vein dumps into the IVC right at the site of the right or an accessory right hepatic vein.
I think this variant is a lot more common that's in the literature, because I feel about 1 out of 10 patients, I am putting some reverse curve catheter in the right hepatic vein and twerking it to find that adrenal vein. It's very close or even within that hepatic vein in my experience.
[Dr. Aparna Baheti]
I don't want to get ahead of ourselves with the procedure, but yes, that is awesome. I'm glad that we're going to talk about some of the intricacies of selecting that right adrenal vein. What labs do you get the morning of the procedure?
[Dr. Fritz Angle]
Well I get a stat potassium level. There is some thought that low potassium levels will mask the aldosterone gradient, and so if they're well below normal, I'd give them some potassium supplements, inter-procedural pre-procedural. Of course, extreme hypokalemia can be dangerous so I'll get a stat potassium level. That's really the main thing I look for that day. Otherwise, it's a venous procedure so whatever your standard is for any other central line placement you do, which probably not too much...
Post-Procedure Protocols for a Successful Adrenal Vein Sampling
A key indicator of successful sampling is evaluating the cortisol levels to determine the selective index. This involves ensuring the cortisol level in the adrenal gland is at least two to three times greater than in peripheral samples. Additionally, the aldosterone levels, which are typically diluted, are corrected using cortisol levels as a dilution marker. It is important to check the aldosterone to cortisol (A/C) ratio for both adrenal glands, seeking a fivefold difference to confirm lateralization. Dr. Angle notes that about two-thirds of cases lateralize, and the absence of lateralization, often due to bilateral adrenal hyperplasia or multiple nodules, should not be seen as a procedural failure. It is important to resume standard medications through the endocrinologist and maintain direct communication with patients, reinforcing the value of integrating clinical practice with procedural expertise.
[Dr. Aparna Baheti]
Now, you've already alluded to this, but you do not keep the patients in the room to await the results, correct?
[Dr. Fritz Angle]
Yeah, that's right. I used to call them the next day once I got the cortisol levels back because that'll tell you if you did your job if the sampling was technically good or not. I look at those cortisol ratios. It should be two to three times greater in the adrenal gland in the periphery on the non-sim, and at least three to four times greater on the stim samples because cortisol levels do go up with ACTH. I call them and say, "Hey, we got a good sample," or, "Gee, do you mind coming back and letting me try again?" I do ask them, and in fact, I tell him, before we even do the case, I say, "About 5% of the time, the sampling doesn't work out, and if you don't mind, I'm going to try again."
[Dr. Aparna Baheti]
Yes. We've talked about this, but do you think that this is a procedure that should be done in private practice if we're not seeing more than 10 cases a year?
[Dr. Fritz Angle]
I really do. I think that from an IR standpoint, it's a safe procedure. You've got the catheter skills, you should offer this, there's just no reason not to, and hopefully, I've convinced you the screening and the supplies you need are very basic. Probably the most important thing is just you need a good endocrinologist, and hopefully, a local surgeon that's willing to do adrenalectomies, but obviously, they get set up the road for that too. So if you're just working with a good endocrinologist, and he wants a service, yes, go for it, call me, I'll walk you through it, it's easy.
[Dr. Aparna Baheti]
I've shared this on prior episodes, but one piece of advice I have for trainees going out into practice, if you practice in a completely different timezone than where you trained at, find some mentors who live in your timezone. It's not fun to call people from back east when it says 7:00 PM. Well, we've gotten a little bit off track, but walk me through the interpretation of the results that you get.
[Dr. Fritz Angle]
Right. You're going to get back cortisol levels initially, and then for a lot of places [aldosterone] is the send out. We now have it in-house, but even then they run it once a week, so it comes later. First thing is I go through those cortisol levels, and I'm just looking to see, is that right side two times or three times greater than the peripheral sample and that tells me I've done my job. That's called the selective index. You don't even need to know that name but the selective index is basically just that ratio.
Then the aldo levels come back and the aldosterone levels are always diluted. Even though you've got a catheter right in the right adrenal, that site hole might be in the IVC. It's partially diluted. The right and left cortisol levels will always be different and that doesn't matter because the left one often you don't put the catheter in the right adrenal vein, so it's actually lower than the right cortisol levels. We correct the aldo levels by using the cortisol levels as a marker of dilution because whether they've got a functioning aldo or not, the cortisol levels are relatively constant in both glands.
So you get an A/C ratio for the right and an A/C ratio for the left, and then you want to compare the A/C ratio for the right and the left. There should be about a five times difference, one side or the other with stimulation to call it a lateralization. As simple as that. First, you figure out the selective index, which is really where the IVC numbers are important, and then you are looking for the lateralization index, which is really just the A/C ratio right compared to the left.
[Dr. Aparna Baheti]
What percentage of your cases would you say lateralize?
[Dr. Fritz Angle]
So in the literature, in my practice too, I'd say it's about two-thirds maybe it's a little bit more than that. A lot of people have bilateral adrenal hyperplasia or they have multiple nodules. Surgery's not going to fix their problem. So that's okay. Don't feel like you've done something wrong or didn't get the result you're looking for. As long as you got a good selective index, then don't expect it to lateralize every time, and not everybody gets an operation and that's okay.
[Dr. Aparna Baheti]
That's a very, very good point. Post-procedure, anything that you've seen that people who are doing this procedure should know in terms of patient follow-up or unexpected side effects?
[Dr. Fritz Angle]
Not really. It's really a very safe procedure. We do pretty much our standard post-venous femoral access observation. I don't routinely do follow-up blood work on them. I just get them back on their usual meds, which again, I leave to their endocrinologist or referring practitioner and that's it. Just get a phone number, give them a call.
[Dr. Aparna Baheti]
Fantastic. I'm sure patients appreciate hearing from you the next day. Just you know I'm sure they're anxious about how the procedure went. One of the things that we really try to stress now, especially to younger trainees, is how important it's to have a clinical practice and not just be the proceduralist. That's another step towards showing that you are invested in their care and that you might need a chance to do the procedure again or that you were successful.
Podcast Contributors
Dr. John Fritz Angle
Dr. John Fritz Angle is the division director of vascular and interventional radiologist and a professor with University of Virginia in Charlottesville.
Dr. Aparna Baheti
Dr. Aparna Baheti is a practicing Interventional Radiologist in Tacoma, Washington.
Cite This Podcast
BackTable, LLC (Producer). (2023, June 2). Ep. 328 – Adrenal Vein Sampling [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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