Potassium often seems like “just another lab value,” yet it has a direct effect on how the heart works: if levels are too high or too low, it can lead to serious heart rhythm disturbances. In this post, we take a closer look at why potassium balance is so sensitive in kidney disease, which foods and medications can raise or lower potassium levels, and what to watch for in everyday life. If you would like to better understand why potassium is checked from time to time, this video will help put the pieces together.
The content of the video in written form
Hello, this is Dr. Zsom.
Dear patients, today we are going to talk about potassium. What is the relevance of potassium for a kidney patient? Well, when you hear about potassium in the dialysis center or in your nephrology clinic, it usually comes as a negative: “Okay, your potassium is too high; you have to be careful not to eat certain things.” Okay. So sometimes we do not appreciate how important potassium really is. Well, cellular function is, in general, heavily dependent on potassium. All cells need potassium, and a lot of it. However, potassium is very closely regulated; high potassium or low potassium, both can cause problems. And if we look at CPR protocols, then we see that both hyperkalemia—that is, high potassium—and hypokalemia—that is, low potassium—can cause major problems such as cardiac arrest due to arrhythmias, such as this ugly thing here. This is normal on your EKG, and this ugly thing is caused either by hyperkalemia or hypokalemia. So, potassium is very closely regulated, and if there is a problem, both high and low potassium can cause major, major problems.
Also, muscle function in general requires potassium. If your potassium is low, it can cause muscle cramps and all kinds of other problems. So, vascular function also requires potassium; a low intake contributes to the development of high blood pressure. Okay. And this is something that we have known for a long, long time. Now, the problem, of course, is that high-potassium foods are generally the healthiest of all foods. Okay, green leafy vegetables, seeds, raisins, potatoes, tomatoes, avocados, beans—these are very healthy and they are generally very good for your blood vessels. Okay. So, if you are put on a low-potassium diet, then you are not supposed to eat what is otherwise the best for you. So, what can we do about that? These are some of the very beautiful fruits that are especially high in potassium, okay, such as melons and cherries and chestnuts and even poppy seed and walnuts. These are very, very good for you in general. So, when you are on a low-potassium diet, then you can’t eat a lot of any of these.
So, what can we do about this? Now, of course, sometimes less than healthy foods also contain a high amount of potassium, such as red meat and all kinds of soft drinks. Now, it has been shown several times and in multiple studies that high potassium intake is associated with a healthy diet, so that, unsurprisingly, it is also associated with lower risk of cardiovascular disease, and this, of course, is in the general population. So, we are talking about non-kidney patients. Okay. So, if this result from a study is more to the left, that means that there is a benefit in terms of cardiovascular disease in general, or stroke, or coronary heart disease from a higher potassium intake. And you see the trend: the more potassium you eat, the healthier you tend to be later on, avoiding all these kinds of vascular problems. The same thing is the case with blood pressure. So you see, most of the studies show that people who have higher potassium intake tend to have a lower blood pressure, so that you can benefit from all these high-potassium-containing foods in terms of blood pressure control.
Potassium is important, so it is very highly regulated. This is very important to recognize. Whatever is important in the human body is also very closely regulated. And the problem arises once this regulation is disrupted because of kidney disease, for example. And the way potassium is regulated is by multiple means. One of the key players here is a hormone called aldosterone. So you eat healthy, nutritious foods that are also very high in potassium, and yet you do not drop dead after a healthy meal because there is aldosterone. So, aldosterone is produced when the blood potassium rises or when you have too little salt in your body. It targets the kidneys, and then potassium is more reabsorbed so that you have less potassium loss through the urine, and also sodium is reabsorbed so that you avoid problems arising from dehydration, for example. So, it is very important because it makes you survive after a healthy meal.
However, aldosterone and the related hormone angiotensin II—oh yeah, this is the substance, angiotensin II, that has that receptor serving as an entry for SARS-CoV-2, the COVID virus, to get inside cells; how did it get into that virus? Well, when angiotensin II or aldosterone are overproduced, they can cause all kinds of problems. For instance, if you have a lot of adipose tissue, then aldosterone is often overproduced, causing sodium retention so that you have too much sodium in your body, and that will lead to increased blood pressure. But not only that, you have arterial stiffening; you will have stiff vessels. You have scarring in the kidney causing chronic kidney failure. You have stroke risk and you have fibrosis. So essentially, the heart will transition into more of a scar-containing muscle. So there are a lot of scars causing electrical problems and all kinds of other problems. Okay. So, aldosterone is very important, but when it is overproduced, then there are major issues arising.
So, several blood pressure-lowering and kidney- or heart-protecting medicines block aldosterone or angiotensin II, their action at least, creating a potential for potassium retention. So here’s what happens: you try to lower your blood pressure, you try to protect your kidney and your heart, and as a side effect, there’s potassium retention so that your potassium tends to be high, and they put you on a low-potassium diet which prevents you from eating the healthiest foods possible. So, this is not good. In advanced kidney failure and several specific kinds of kidney diseases, even without kidney failure, potassium secretion will decrease; diabetes is such a disease. Also, if someone is dehydrated, aldosterone and angiotensin II are actually very necessary because they mitigate the effect of dehydration on the kidney by reabsorbing sodium so that you have sodium retention and more of the needed salt is retained in your body. Okay.
And remember, very important: dehydration is a misnomer; very often, dehydration means that you have both salt and water losses. Water in itself does nothing to the kidney. Okay. When you are dehydrated, that means that you lost both salt and water. So, blocking aldosterone and/or angiotensin II sometimes, in specific circumstances, can be quite risky, because as I said, in any case where you have dehydration, then you need aldosterone and angiotensin II. And so, you end up with acute kidney failure and high potassium values. So add to that that anti-inflammatory drugs such as ibuprofen, diabetes, certain transplant medications, and certain potassium-sparing diuretics also increase potassium levels by decreasing potassium secretion into the urine. Okay. So that if you take something like an ACE inhibitor, for example—so a medication that decreases angiotensin II action—or an aldosterone blocker such as a special diuretic, then you will end up with high potassium. And add to that ibuprofen or a transplant medicine, and you may have a problem. So, your very healthy diets can turn into very dangerous ones in certain situations. They can cause high blood potassium, arrhythmias, and even cardiac arrest.
Now, in hemodialysis patients, this whole thing is compounded by yet another problem, and that is that your potassium removal by the dialysis machine—since your kidney is not able to remove potassium, or at least not enough—is limited to three times a week and only four hours during those days. So what happens then? Well, here’s a study, an old study but a good study, which tells you that from the start of dialysis, what are the most dangerous times when you tend to have arrhythmias and sudden cardiac death? Well, right after the start of dialysis when the potassium levels fall, because all of a sudden you remove all the potassium that you ate for 48 hours before. Okay. And then you are fine for a while, and the more time passes after dialysis, the more likely it is that you are going to have high potassium and therefore heart problems. Okay. So you see that potassium is very important in terms of how you do your dialysis and how you diet in between two dialysis sessions.
So, what are we going to do? What is the solution then? Well, the most important thing is to be safe. And to be safe, kidney patients need potassium level monitoring at regular intervals. The more potassium is a problem, the more often you have to have your potassium levels checked. Your nephrologist will determine how often you need that checked based on your specific condition. And remember, specific condition means your specific individual situation. Okay. There are a lot of factors that the nephrologist will have to consider. And then the nephrologist is going to tell you how often it is safe for you to time your potassium checks. Maintain a balanced diet. So if you eat relatively balanced—and that means that you don’t suddenly introduce something entirely new and then eat a lot of it, but without bouts of high potassium intake, you maintain a well-balanced diet—then you arrive at a golden mean and you have much, much, much fewer problems with high potassium.
Now, of course, all of this will change if you have diarrhea, for example. If you have very low potassium intake and yet the potassium is going to go out with your diarrhea, then potassium needs to be replaced, because low potassium can cause just as much problems as high potassium. So, one needs to know all the medications one is taking; carry a list and show it to your nephrologists. Okay. Because on the basis of that, your nephrologist will be able to determine how much risk you have for high potassium or even low potassium. Avoid anti-inflammatory drugs as much as possible because they tend to cause high blood potassium and they tend to lower your kidney function. And potassium tablets are not automatic even if you are taking a diuretic such as furosemide, because kidney patients may need a diuretic such as furosemide exactly to lower their potassium, and that is one of the best treatments when your potassium is high or to prevent a high potassium.
So, the nephrologists need to know about changes of blood pressure medications, changes in heart protective medications, and transplant medications because, based on this, your risk profile can be established for high potassium or even low potassium. Sometimes diuretics may cause low potassium with kidney disease, but much less so. Diarrhea, vomiting, and fever may cause both dehydration and low potassium. So that even high potassium can occur if your kidney function goes so much down that your kidney almost stops working. So in these circumstances, it’s advisable to temporarily hold your aldosterone blocker medications and angiotensin II blocker medications. Okay. Ask your nephrologist about this because often I saw that patients, even when they are very severely dehydrated, they take their blood pressure medications and they take their heart and kidney protecting medications, and they end up with very low kidney function and high potassium levels.
By the way, this is me a little bit younger. So, even on dialysis, diarrhea, vomiting, and fever may lead to a lot of loss of potassium and salt. So you can actually get dehydrated and develop a low potassium level even on dialysis if your diarrhea is severe enough. And in a situation like that, you may want to stop diuretics and drink a little bit more, eat a little bit more salt. And most importantly, your dialysis needs to be adjusted. You see, in the dialysis machine, we can change the potassium concentrations so that we can adjust to your situation, but you need to get your potassium checked. Now, in PD, in home dialysis, we can also put potassium in your dialysis so that we can adjust your dialysis treatment according to your needs.
So, if potassium is high due to an increase in the dose of your medications, then there are treatment options. Okay. For instance, you may get furosemide, or there are certain specialized medications that you can take that lower your potassium through the gut. Okay, there are some new ones in the clinical setting right now. In these situations, you dissolve these medications in water and then you just take it according to what your dialysis doctor or your nephrologist tells you. Also, you might want to take some bicarbonate powder; okay, you also dissolve that with water and then that will counteract the diuretic action of furosemide while maintaining its potassium-secreting health assistance. So there are several options, but these options can be considered once we know what your potassium level is. And if you are taking such medications, or if you develop a new disease, or there are those changes in these medications, then we need to know about it. Some of the blood pressure, heart, and kidney protective medications may need dose reduction and even elimination in certain circumstances.
And even elimination in certain circumstances, such as, for example, if you have impaired kidney circulation—and many people somehow believe that impaired kidney circulation means dehydration; no, there are a whole bunch of other problems that can cause impaired kidney circulation. For example, vascular disease, you see, low blood pressure of any cause. For example, acute illness like an infection, for instance, can cause decrease in blood pressure, or if you have lung problems that can cause it, or you have heart conditions such as heart failure or even severe sleep apnea that can also cause it. Okay. So if you have these diseases, then your nephrologist needs to know about it, and then your nephrologist may reduce or even eliminate certain medications to increase the blood flow, the circulation to the kidney, so that the kidney gets more oxygen. If the potassium is very high, you may need to take some of these specialized medications. Some might interfere with bowel function and may give you extra salt, so again, your nephrologist will decide which one is appropriate in your situation.
Low potassium, on the other hand, may need to be replaced, and this could be, for example, a potassium pill along with maybe a magnesium pill. But sometimes your potassium is so low that potassium needs to be given IV. Okay. So if your potassium is low, then don’t be surprised that your doctor is going to direct you to the emergency room so that they can give you IV potassium. This is to protect your heart so that you don’t develop cardiac arrest due to arrhythmias. Okay. So, irregular heartbeat in a low potassium situation is very unhealthy; you don’t want to leave that untreated. Okay. So in such situations, it is very important to talk to your nephrologist so that your nephrologist can determine how often you need your potassium checked, and then your therapy may need to be changed and thus the problems can be prevented.
But what about diet? I said that high-potassium foods are also very healthy for you. So what can you do about that? Well, first of all, transplantation is a very good option. But even then, of course, transplantation medications may cause a problem. But also, if you are on dialysis or you are close to dialysis, you may eat a little bit of potassium-containing healthy foods; it’s just it needs to be steady. Because keep in mind that whenever we check your potassium, it’s a snapshot. Okay. So we don’t know what you did the day before or the day before that. Try to keep things very steady and then, empirically, by checking your potassium, we can tell you if you’re doing well or if some things need to be adjusted. So with all of that, thank you for your attention and goodbye for now.
