The Rest is Kidneys

Bananas are not the problem! Hyperkalaemia and CKD

• North West London Kidney Care • Season 1 • Episode 1

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The Rest is Kidneys podcast series is brought to you by Imperial College Healthcare NHS Trust and North West London Integrated Care Board (NWL NHS)

In our first The Rest is Kidneys episode, Dr Andrew Frankel and Prof Jeremy Levy, Consultant Nephrologists at Imperial College Healthcare NHS Trust, discuss hyperkalaemia (high potassium levels), particularly in patients with chronic kidney disease (CKD). They explore when clinicians should be concerned about elevated potassium levels, the causes behind hyperkalaemia, and the best approaches to managing it in primary care. The episode aims to demystify the condition, provide clarity on when action is necessary, and offer practical tips for managing hyperkalaemia without unnecessary panic.

Key points include understanding spurious hyperkalaemia in primary care, recognising when potassium levels are truly concerning, and the role of commonly prescribed medications such as ACE inhibitors and angiotensin receptor blockers. The doctors also discuss treatment options like potassium binders and diuretics, emphasising the importance of maintaining heart and kidney-protective medications where possible. The episode also touches on the role of diet in managing potassium levels, clarifying misconceptions about potassium-rich foods and their impact.

Key Takeaways:

Spurious Hyperkalaemia: Often caused by delayed blood sample processing in primary care.

When to Act: Potassium levels above 6.5 mmol/L warrant urgent action. Levels between 5.5-6.5 mmol/L require follow-up but are not emergencies.

Medications: Certain medications, especially ACE inhibitors, ARBs, and mineralocorticoid receptor antagonists, can cause high potassium but are essential for heart and kidney health. New potassium binders, such as Lokelma and Veltassa, can help manage potassium without discontinuing these vital drugs.

Dietary Considerations: Bananas are not the only source of potassium. Many fruits and vegetables contain high levels, but stopping their consumption is not advisable. A balanced approach to diet is key.

Educational Resources: Potassium education sheets are available on the North West London CKD site.

This episode is a practical guide for primary care clinicians on managing potassium levels in CKD patients and balancing treatment urgency with patient well-being.

We hope you enjoy this episode. 

Resource Links:
NICE GUIDELINES [NG203] chronic kidney disease: assessment and management Overview | Chronic kidney disease: assessment and management | Guidance | NICE

Northwest London CKD guidelines for primary care Chronic kidney disease (nwlondonicb.nhs.uk)

Renal association: Management of hyperkalaemia in the community (algorithm) APPENDIX 5 - HYPERKALAEMIA ALGORITHM IN COMMUNITY.pdf (ukkidn

The purpose of this podcast is to inform and educate health care professionals working in the primary care and community setting. The content is evidence based and consistent with NICE guidelines and North West Guidelines available at the time of publication.

The content of this podcast does not constitute medical advice and it is not intended to function as a substitute for a healthcare practitioner’s judgement.

Produced by award-winning media and marketing specialist Heather Pownall of Heather's Media Hub

Welcome to North West London Kidney Care Podcast. A bitesize podcast where Chronic Kidney Disease Management is made easy for healthcare professionals in primary care.

Jeremy Levy
So hello and welcome to this, our very first podcast about chronic kidney disease. And today we're going to be talking about a topic that really causes lots of anxiety, which is hyperkalemia,  high blood potassiums.

Andrew Frankel

Hello everybody, my name is Dr Andrew Frankel, and I'm a Consultant Kidney Doctor working at Imperial College Healthcare NHS Trust. And with me today is, of course…


Jeremy Levy

Jeremy Levy, I'm also a Consultant Nephrologist at Imperial Healthcare NHS Trust, and we're going to be talking potassiums.


Andrew Frankel

Yes, in this episode, we're going to talk about the problem of hyperkalemia, or high blood potassium, particularly in patients with CKD. We hope by the end of this session, you'll have a clear idea of when to get worried, and how to manage hyperkalemia. And you will be less worried about this whole difficult topic.


Let me start. Jeremy, can you start by telling us, what do we mean by hyperkalemia, and when should we be worried about it?


Jeremy Levy

Really important starting point, and I'll come to some numbers in a second. But first of all, to remind you, which I'm sure you all know, very often, a blood potassium that's reported as high in primary care is often completely spurious. People get panicked. They get rechecked three hours later in an emergency department, and the results are completely normal. And the reason for this is that blood samples, particularly in primary care, can sit around for some time before getting to a lab, and some of that causes potassium to leach up from cells, and to cause essentially, a spurious hyperkalemia. And that's a very common problem from blood samples taken in primary care.


But of course, this doesn't mean we can ignore every potassium result, and we’ve got to get this balance right, about when it is significant, and when it isn't. And everything we're talking about today is in the setting of people with Chronic Kidney Disease, rather than just everybody else. But the tips and tricks are all the same

And finally, in terms of background information, don't forget that the lab reports of abnormal potassium and abnormally high potassium above a level (labs very slightly), but of about 5.2 mmol/L. But we as nephrologists certainly, really don't get worried until the potassium is over 6 mmol/L. So there's a wide range where the results, yes, are abnormal, and patients might get frightened because it's labelled red, and you and your staff may get worried, but actually people are not going to come to substantial harm in this very large range, from 5.2 up to 6, and from 5.5 to 6 is only mild hyperkalemia. From 6 to 6.4 would be labelled moderate hyperkalemia, and it's only severe hyperkalemia over 6.5 mmol/l. So there’s much more scope and space for dealing with the problem, rather than having to get on the phone to a patient immediately and cause panic.

And assuming that the person, and the patient is well, therefore, you only need to be really worried when it's over 6.4 or 6.5 mmol/l. That's certainly a place for urgent action, and the much more normal lower results between sort of 5.5 and 6.5 are important to check, but it's not super urgent. Does not need a phone call in the middle of the night. And in reality, in chronic kidney disease, hyperkalemia is not usually a significant issue until people have got the most severe forms of chronic kidney disease, with the caveat that we're going to come to, that the drugs they're on may cause a problem earlier, but much more in stages 2 and 3 Chronic Kidney Disease, this is much less of a problem as it tends to be worse with more advanced Chronic Kidney Disease. So really worried over 6.5. 5.5 to 6.5 yes, some actions, but not super urgent, and up to 5.5 we're really not worried at all.


Andrew Frankel

Thank you, Jeremy, that's really helpful. And so essentially, critically appraise when the result comes in as hyperkalemia. Consider the timing of the blood test, the level, what else might be going on, and whether the patient is unwell, in deciding what you're going to do. But before we come on to what we're going to do, I'm going to ask you another question for background, which is, what are the common reasons for higher serum potassium levels in patients?


Jeremy Levy

As I mentioned earlier, in primary care, a very common reason is blood sitting around some time before they get to the lab. Most potassium is actually inside cells, and if cells lysis, they just release potassium. And so blood sitting around getting lysis can lead to spurious hyperkalemia, and this can happen worse under certain circumstances. So that is a very important reason for spurious hyperkalemia.

In terms of real hyperkalemia, the most common reason is, in fact, drugs, drug induced hyperkalemia, and these are the drugs we keep talking about because they're so important for kidney and cardiovascular health, but they do cause high blood potassium. So that's the renin angiotensin system blockers, the ACE inhibitors, angiotensin receptor blockers, and more commonly, now, the Mineralocorticoid Receptor Antagonists. So this group of renin angiotensin blockers, and particularly when used in combination, which happens in, of course, chronic kidney disease and, for example, heart failure. And those are particular risks because all of those drugs do it.


But then there are some other medicines that can also elevate serum potassium, and some of these are quite commonly used. So for example, trimethoprim, particularly in people with Chronic Kidney Disease, can push up serum potassium and, interestingly, non steroidal anti inflammatories can, these are transient effects, and are not usually very significant, but if you had mild Chronic Kidney Disease, it can make it worse. So trimethoprim, non steroidals, but most importantly, all these heart and kidney protective drugs. Very rarely, people who binge on certain fruits might do it, but this would be very transient. But you know, a whole tray of Alfonso mangoes, or two kilograms of cherries, because they happen to be on the fruit stall in front of you, but that's unlikely to cause major problems.


Andrew Frankel

Yes, we're going to come back to diet a bit later on, but I'm going to now ask you, having told us a little bit about what hyperkalemia is, and its potential causes. You’d better give us some advice now, about how this is managed. What do you do, and in what time scale from a primary care perspective?


Jeremy Levy

Great, yeah, that's really the critical thing. And just if you want some other background, there's some really simple, straightforward flow chart that's both on the North West London guidance websites, and the UK Kidney Association. But I'm going to summarise some of that information now.


So timescales, so we've already mentioned this, but potassiums of up to 6 mmol/l in people who are well, really don't need a midnight phone call. So yes, you might get the results and it might come back late, 6/7pm, it can wait until the next day, up to 6pm. It doesn't need an emergency contact with the patient, if the patient is not unwell. And hopefully you may have known that when they had their blood test. If the patient's not unwell, a potassium between 5.5 to 5.9, which is mild hyperkalemia, does need rechecking, but that can be done within the next 3 to 5 days, not hours, days. That's 5.5 to 5.9.

If the potassium is up to 6.5, which is sort of moderate hyperkalemia, the patient does need a phone call to see how they are, check there are no new medicines that may have caused it, and they also need a recheck, and for that within the next 24 hours. So potassium is between 6 and 6.5, a recheck within 24 hours.


Now, if the potassium is over 6.5, that's the one that is an emergency, is an urgent issue, and they need their potassiums rechecked immediately. That's the group of people in whom they may well need to be sent to an emergency department to recheck their potassiums, if it's over 6.5 but not, as I said, if it's 5.6/5.7. So 6.5 and over, bad issue.


Andrew Frankel

Yes, so just to reiterate, and I know we're banging on, so a very clear message. It's really in the person who is well, it's 6.5 and higher that needs that urgent reassessment. Otherwise, you can do this in a much more planned manner, either the next day if it's 6 to 6.5 or even up to the next 3 to 5 days if it's 5.5 to 6.


Jeremy Levy

Yeah, absolutely correct. You've got it, short term memory is good Andrew, you're not yet losing cognitive function.


Andrew Frankel

Pleased to hear that!


Jeremy Levy

Let's talk about management now we've got timescales, right. So the first thing is to check the medicines. As we've already mentioned, often, this is triggered with a background of some sort of medicine. There's often some other event, maybe a new medicine. But do check what medicines the person is taking, and this issue of an intercurrent illness, or an extra medicine. If there is an obvious new drug, then clearly stop it. So if a person has just been started on a new angiotensin blocker, and their potassium is now significantly high, then they may need to stop the new drug.


So first of all, it is certainly worth checking the medicines that the patient is taking, and that they haven't got an intercurrent illness. If they have just started a new angiotensin block or an ACE inhibitor, this may need to be halted temporarily or the dose reduced. If the potassium was over 6.5 then certainly you need to stop those drugs. If it was only 5.5 to 6, then they can be continued, but may well need just the dose being reduced.


So drugs and medicines are very important, but these drugs are actually critically important for people with heart failure or Chronic Kidney Disease. They're the only medicines that reduce death rates, reduce morbidity, stop hospital admissions. So we do want to continue them wherever possible, so it's getting this balance right. May need a dose modification, but try and continue them if we can. Do ask people about what they've been eating. Very rarely, as change in diet may have contributed to hyperkalemia, but it's not very common. If the potassium is in that range between sort of 5.5 and 6, it certainly needs rechecking, but then they don't need their medicine stopped, and they can certainly continue with their angiotensin blockade or other protective drugs.


If the potassium is over 6, and we've reduced the dose of the angiotensin blocker and rechecked it, and it's still hovering somewhere around that level, we then have a dilemma. We've got medicines that are really important for hearts and kidneys, but yet a potassium that's running too high. But now we do have new ways of tackling this, and these are the new potassium binding agents. And on the one hand, it's sort of counterintuitive to give another medicine to solve a problem, but we do know that these medicines are just so important. They stop people dying early, they prevent strokes, they prevent progression of cardiovascular and Chronic Kidney Disease. So where possible, we want to do everything we can to continue ACE inhibitors, angiotensin blockers and the Mineralocorticoid Antagonists.


So these new potassium blockers have been really helpful, and clearly can lower potassium, chronically and acutely, which is not for today's talk. And there are two of them around - one is called lokelma, or sodium zirconium cyclosilicate (and near impossible saying that one!) and the other is veltassa, or patiromer. Both are NICE approved, both available to be prescribed in the community, although are meant to be (sadly), started in secondary care settings. And their primary aim is to allow us to continue with renin angiotensin blockade, while controlling the potassium. And in general, we use these if the potassiums are over 6, and therefore we can't continue renin angiotensin blockade, or if potassiums have been consistently just under 6, in that range of sort of 5.6 to 6, where we really do want to continue maximum dose. So we don't start them at lower potassium, but these can be very useful, and then are often needed to be continued long term.


And then the last treatment would, of course, be diuretics. So diuretics are incredibly helpful. Clearly, if you have heart failure or fluid overload, or peripheral edema, they can be symptomatically helpful, and especially in that setting, but diuretics will also lower potassium, and it may well be that the thiazides are better than loop diuretics, and it really doesn't make a huge difference. But adding in a diuretic to renin angiotensin blockade can often bring the potassium down very helpfully, and allow us to safely continue these other medicines. So acute hypokalemia, a different topic we won't cover today, but persistent hyperkalemia, adding in a potassium lowering agent binder may be really helpful.


Andrew Frankel

So that's really a beautiful description of all the treatments that are available, and are available in primary care. Admittedly, the potassium binders need to be commenced either in secondary care, or on secondary care advice. But there's a lot of interventions. And one of the concepts I always try to highlight is that when you start an inhibitor of the renin angiotensin system, you should anticipate that potassium may rise. It's not a sudden, idiosyncratic, adverse event. It's a predictable, and to some extent, preventable problem. If you're already thinking, I must make sure the patient knows, for instance, not to use non steroidal anti inflammatory drugs, shouldn't be given trimethoprim and so forth. So remember, with RAS inhibitors, these really important life saving medications, this is a predictable event after starting them.


So I know you did mention a little bit about cherries. I know you're very keen to talk a bit more about food. I think diet is really important because I understand that our approach to the dietary management has changed. Do you want to highlight some of that Jeremy?


Jeremy Levy

Of course, and I'm not obsessed by cherries, but we're recording this just after cherry season, they happen to be on my mind! And as you say, most people have often gone to Dr Google, haven't they, and they've looked up diet and kidney disease, and apart from the first five screenshots that are all selling them products that will be helpful (none of which are), most of the time, people just get told to stop eating bananas. And there's this myth around that bananas are particularly high in potassium. Actually, for example, avocados, cabbage, potatoes, salmon, beans, they've all got more potassium per 100 grams than bananas do. So bananas are not the problem. All plants contain lots of potassium. All fruits contain lots of potassium. There are fruits and plants that contain more and less potassium. But the problem we now recognise, is if we tell people to stop eating fruits and veg because their potassiums are high. Of course, they're avoiding what we know are critically important dietary constituencies for overall health, and eating a plant rich diet, a diet richer in plant based foods, is incredibly important for protection from cancer, cardiovascular disease, and general health.


So what we've moved now much to, is this appropriate balance, and not stopping people eating fruits and veg, which are critically important for their overall health. So diet sheets that we often use now in some people, are often just showing people higher and lower potassium foods and saying, be careful with those that are higher in potassium, and eat more of the lower potassium foods. But it's not about stopping eating fruits and veg which are so critically important. And the reality is, if people have only got mild hyperkalemia (potassiums of up to 6), it is nigh on impossible to make this worse from diet. And dietary advice really isn't so relevant in that setting. Potassium’s of over 6, then it is going to be more helpful. But again, as we've alluded in other episodes, getting the language right is really important, and not stopping people eating food, that in other settings is going to be so important for their overall health. So diet, yes, has some impact, but not telling people to stop eating foods, and it's not just bananas. But in general, diet is probably not the most important factor.


Andrew Frankel

That potassium education, rather than low potassium diet sheets, is a new approach. And those potassium education sheets will be available on the North West London CKD site, and easily accessible and downloadable.

That was really helpful, Jeremy. I want to finish by just stressing those key points, that we really only need to be worried if the patient is unwell, or if the patient has a potassium of over 6.5, below this if they are well, this is not a medical emergency. Certainly you will need to recheck the potassium, but you can do that in a more leisurely fashion.

Secondly, RAS inhibitors will tend to cause a rise in potassium, and this should be anticipated, but those drugs are so beneficial to people with CKD, and particularly heart failure, and we really want to strive to continue them where possible.

And finally, where you find hyperkalemia in the context of those drugs, and you've done everything else, the new potassium binding agents, lokelma or veltassa, effectively keep the potassium down, and allow you to continue RAS inhibitors. And finally, of course, we shouldn't discourage people from eating fruit and veg. Jeremy, thank you so much for that. That's really helpful.


Jeremy Levy

Andrew, that was a great summary. And actually, your cat's all my fault, of course, because I mentioned the word salmon earlier, and I'm sure that's what's excited her!

Andrew Frankel

Yes, that's what got her started! 


Jeremy Levy

On that point, bye bye everyone!


Thank you for listening, we hope you enjoyed this episode. All information is fully consistent with NICE and North West London guidelines. You can find out more in the show notes and contact us with any suggestions or questions, to do so, send us a text using the text function at the top of your show notes.

In our next episode, we'll be covering an initial approach of CKD and lifestyle. Should we be more liberal with glycaemic control in diabetic kidney disease? How should we adjust the blood pressure targets according to albuminuria? Thank you for listening, please subscribe to the show and we will see you next time!