S02_E24 - Let's Talk Kidneys!

Speaker 1: 0:00

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Speaker 2: 0:04

Welcome to the Healthy Matters podcast with Dr. David Hilden , primary care physician and acute care hospitalist at Hennepin Healthcare in downtown Minneapolis, where we cover the latest in health healthcare and what matters to you. And now here's our host, Dr. David Hilden .

Speaker 3: 0:21

Hey everyone, it's Dr. David Hilden and welcome to episode 24 of the Healthy Matters podcast. This is the final episode of season two, and for those of you who are accounting , this is also our 50th episode overall. Do you know recently I was asked what my favorite organs were in the body and the kidneys came in the top three, but do you know what they actually do? Well, this is the second in a series of episodes we're going to do periodically on the show about the organs in the human body with the help of some of the biggest brains at Hennepin Healthcare. For those of you who remember our first episode was about the colon. Joining me is Dr. Jennifer Wu . She is a nephrologist and a colleague of mine here at Hennepin Healthcare. And we're gonna go over the basic functions of the kidney, the common issues people face with them , and the preventive strategies and treatments for dealing with these issues. Jennifer, welcome to the show.

Speaker 4: 1:12

Hi, thanks for having me. Great

Speaker 3: 1:13

To have you on the show. Now, although I ranked the kidneys number two, you'd probably rank them number one, I put the heart above the kidneys. I don't know why I did that, but you're a nephrologist so you probably likely think the kidneys are the most important organ. But can you just give us a little basic information about what your kidneys are and what do they do?

Speaker 4: 1:31

Yeah, and happy to. Um, so the way I start by telling most of my patients is most of us are born with two kidneys and they're about the size of your fist. So they're about four or five inches , um, from top to bottom in length. And they sit in the middle of our abdomen and they're tucked behind all the rest of our organs. They're behind our intestines and stomach and they sit right behind the , um, right in front of the muscles that we call are flank muscles. So they're really tucked in and they work generally speaking by tiny filters. So blood gets brought to our kidneys by arteries and the arteries get smaller and smaller, and eventually they get down to these microscopic filters. And we have about 1 million filters in each of the kidneys. And what they do is they clean our blood. And so kind of minute by minute and hour by hour they're cleaning out things that we need to get rid of, things like um, extra electrolytes or blood salts and and toxins. And they also may be helping us with other things like our balance of water, balance of salt and things like that. That's

Speaker 3: 2:29

A lot of things. Now you call them little filters. And that leads me to ask you, I know the answer to this, but tell everybody else why are you called a nephrologist?

Speaker 4: 2:38

So the smallest, the filtering unit in the kidneys is called the nephron. So there's a , a cluster of blood vessels and the blood in our body gets filtered through. And I describe it almost like the paper coffee filter in your coffee maker or like a colander or a strainer in your kitchen. What we want is for the liquid part of your blood to be able to freely fall through and we wanna hang onto all of the good stuff, the solid stuff that your body goes to, great pains to make and keep things like protein, blood cells like your white blood cells and your red blood cells, all of that we want to keep in our body and not lose every time we're cleaning our blood. And so that nephron starts with that filter, that cluster blood vessel filter, and then there's a series of tubes that help really determine what needs to stay and what needs to go. So at any given moment, maybe your body's going to keep a little bit more salt or get rid of a little more potassium or keep or get rid of water and those sorts of things. So the , the kidney's fine tuning all the time, you know, even one minute to the next, your kidney may be hanging on to different things in different quantities.

Speaker 3: 3:44

So how does it know how to do that?

Speaker 4: 3:46

It's a complicated system.

Speaker 3: 3:47

It doesn't have its own little brain, but you know, I, I tell students all the time and and other people that like, let's just take potassium. Your body requires potassium to survive every second of the day has to have potassium. But if it has too little potassium or too much potassium, it's downright dangerous and it's the kidney's job to keep it in this narrow range. How does it know how to do

Speaker 4: 4:07

That? Absolutely correct. I think there's a lot of things where I sort of refer to it as the Goldilocks principle. We don't want too much or too little. We wanna keep things just right. So there's a , a complicated series of nerves and channels in the kidney, things that sense chemicals or different concentrations of things. And so there's all these different checkpoints along that nephron that, that filtration tube that really are kind of almost taking a gauge of what's going on. So at the beginning of the kidney, there might be things going on that actually by the time that fluid gets to the later part of the nephron, your kidney may be sensing that we need to change the whole system. And so there's actually a feedback loop that it actually, that nephron can talk to itself. So by the time you're at the end of the assembly line, if you will, there's a signal that can go back to the beginning and say, you know, scrap it, change things. We need to hang onto more salt 'cause we're getting rid of too much and that sort of thing. So that's part of what has made the kidney a really interesting organ to study is that there's all of this almost constant sort of engagement with itself.

Speaker 3: 5:10

So why do we have two of them? Is there , do we know a why we have two? And how is it that we can live with just one?

Speaker 4: 5:16

That's a great question and I don't actually know that we know why we have two. I I suspect that maybe somewhere lung evolution there was a redundancy in a sense our kidneys are so responsible for balance and trying to keep the order of the house, if you will, that it may have made sense, if you will, to have two . But we can, and some of us certainly do live with one kidney, some people were born with just one kidney or over the course of time , um, have to have a kidney removed either because of kidney cancer or injuries to the kidney. And people who have had a kidney transplant live with only one kidney. And on the flip side of that, people who donate one of their kidneys to a loved one and then live the rest of their life with just one kidney.

Speaker 3: 5:58

And so if each kidney has a million nephrons, that means most of us have a couple million nephrons, but apparently one million's enough. Exactly. So you said they're buried kind of deep down in there, they're kind of protected in there, aren't they? They are. And that, you know, I suppose, you know , um, there's a reason for that. They're kind of buried in a little bit of soft tissue and fat and they're deep down in there so that they're highly protected in there.

Speaker 4: 6:19

I think we sort of keep a lot of our most important things protected. Our, our brain is inside of a hard skull and our heart and lungs inside of a a rib cage. And, and I suppose we, we needed some breaks where we could bend over and do things like that. So maybe the, the solution for the kidneys was to just stick 'em deeper in there.

Speaker 3: 6:34

Okay. So we've talked about kind of the high level view of what the kidneys are and what they do. That was really helpful. I wanna go to a real specific problem. Kidney stones, because it's so common and loads of people have them and they hurt like heck start with kidney stones. What are they?

Speaker 4: 6:50

Kidney stones are essentially hard objects that are created from various chemicals that pass through our urine. Most kidney stones are made of calcium, they're , they're calcium based stones and that calcium has to bind with something else to make it harder, a hard substance. And that can be things from our diet or other things from our body. Things like a substance called oxalate or calcium phosphate. And that's actually what makes our bones hard. That makes up 85 or more percent of the kidney stones in the United States. There are a few other substances that also can turn into stones. Things like uric acid, which is the substance that is responsible for gout and a couple of other uh, things. But that tends to be what make up stones. So they're pretty hard substances.

Speaker 3: 7:34

And why do some people get kidney stones? And, and most of us, or many of us never do in our whole life. We all have kidneys, we all eat calcium, we all have all that. Why do some people get them?

Speaker 4: 7:44

It seems like some people are more predisposed. It's not just about having calcium in your body. And actually a lot of folks who have kidney stones, even the ones made of calcium, don't have high levels in their blood. When we do testing, it turns out that for various reasons they may just be getting rid of more calcium in the urine. So there's just more calcium around the kidneys. And once that higher calcium level is present in the kidneys, it just takes one other thing, higher levels of certain things in the diet or not having enough hydration to finally fuse those substances and then make a stone. And then it's almost like a snowball at that point that it'll just tend to grow and grow and grow and then get big enough to cause problems.

Speaker 3: 8:25

Uh , is it men, women, old, young, everybody equal or is , are there some people that are more at

Speaker 4: 8:30

Risk? So men seem to be twice as likely to get stones as women. And the older we get the more likely that we may have a kidney stone. Um, so in our younger years, say if you're under the age of 40, maybe only 5% of the population has had a stone. And by the time we're in our seventies and eighties it may be more like one in five people have had a kidney stone. And

Speaker 3: 8:50

The men thing is , uh, I had some uh, uh, women who have done childbirth before. Seeing you men , you've got this coming to you <laugh>. I have

Speaker 4: 8:59

Heard uh, folks who have had a child and had a kidney stone and they would have a child drug free any day of the week over kidney

Speaker 3: 9:05

Instead of another kidney. Absolutely. I heard they that's I heard can really, really hurt. So why do they hurt so much? I mean the basic thing is this, it's a hard little thing that's moving its way from your kidney down to your bladder so you can urinate it out. But the tube that it has to go through is like the size of a spaghetti noodle or something. It's not very big. Right. Can you explain to us what , what is that pain coming from in a stone? What's going on? So

Speaker 4: 9:25

The kidney stone doesn't hurt when it's in the kidney or when it's in the bladder. You're exactly right, it's in that tube that we call the ureter, which is um, the connection between those two and that ureter is small and it doesn't stretch very well. There's certain parts of our body, things like our blood vessels that have a lot of elastic, a lot of stretch to them, but the ureter isn't very stretchy. So once you get a certain size of a stone, it's just more likely to get lodged and then it's gonna put a little bit of strain on that ureter and the pain that we feel is really the pain of that stretch as the stone is hopefully moving on down. Um, there are times that the stone is big enough that it doesn't move down and then it takes some of our urology colleagues to go in and break up the stone to help it pass easier. And that can be through , um, using sound waves to break up a stone. Or sometimes they have to go in and and do a procedure where they take the stone out with a, like a basket or a grabber.

Speaker 3: 10:16

Okay. So okay, listeners, there's a lot of listeners going, you have to go in there and pound out the stone and take it out. How do you get in there? And I know this is our urology colleagues, but you really, they put a little catheter up inside your bladder,

Speaker 4: 10:29

They put a catheter in the bladder and while you are uh , sufficiently asleep, I'm

Speaker 3: 10:33

Assure hopefully you're sufficiently asleep,

Speaker 4: 10:35

Quite asleep, then what they'll do is they'll take a small camera and they'll be able to uh , use a , a , a wire or some technology to be able to go up and grab with a little basket or a small

Speaker 3: 10:45

Hand .

Speaker 4: 10:45

They don't take

Speaker 3: 10:46

A little pickax like a minor and instead of like chiseling away at this thing, huh

Speaker 4: 10:49

I from how painful the stones are, that that might be something people ask for, but no , our urology colleagues are , are more humane than that .

Speaker 3: 10:55

Okay. So, so it sounds to me like there are ways to get rid of them. Either they pass on their own, might hurt a little bit or a lot of it , but it's gonna pass or they're too big. And then you have to call a , a specialist in to come in and retrieve the thing. A better route than any of that to me sounds like. Okay, how do you prevent this in the first place?

Speaker 4: 11:13

Prevention is a a much better strategy answer .

Speaker 3: 11:15

Can you prevent them or are you just doomed if you're, if you're one of these at risk people.

Speaker 4: 11:18

So oftentimes it unfortunately takes a first kidney stone to determine that you are a person at risk for kidney stones. The biggest piece of advice that I I give anybody is to hydrate more, hydrate better. That lets that calcium or or whatever substances dissolve a little easier. And that way you can pass them more freely once you pass a kidney stone , um, and you know that you are at risk beyond just hydration, there are certain tests that we can do in the kidney world. We can have you either collect a sample of urine for, for the course of 24 hours. We can send that off to a special lab and and determine if there are other risk factors, either other medications or other recommendations to your diet that we may be able to help with. Some people who pass more than one kidney stone or who we know have more kidney stones in the kidneys that haven't passed yet may go home with a strainer and try to collect a sample at home. If you are able to collect a sample, you can bring that in and we can run tests on that in the lab to figure out what kind of stone you have.

Speaker 3: 12:15

You brought up hydration. I have never known a nephrologist to not talk about hy hydration. So that's a little insider tip to the listening world. Your nephrologist always wants you to stay well hydrated and I'll be happy to tell you that Dr. Ru is here with her water bottle right here, right now. So <laugh> , we're gonna take a short break and when we come back we're gonna talk about chronic kidney disease, the other things that can go wrong with your kidneys and what measures you can take to prevent the development of kidney problems down the road. So stay with us and we'll be right back.

Speaker 2: 12:47

You are listening to the Healthy Matters podcast with Dr. David Hilden . Got a question or comment for the doc, email us at Healthy matters@hcme.org or give us a call at six one two eight seven three talk. That's 6 1 2 8 7 3 8 2 5 5. And now let's get back to more healthy conversation.

Speaker 3: 13:09

And we're back. We're talking to Dr Jennifer Wu who is a nephrologist that is a kidney doctor with me here in downtown Minneapolis and Hennepin Healthcare . Thanks for joining us on this show about your kidney beans . So Jen , talk to us about the common things that can go wrong with people's kidneys as we get older.

Speaker 4: 13:28

So one of the common things that I see in my clinic is a, a disease or a condition called chronic kidney disease and that just really means the kidneys aren't able to do all of the jobs that they normally do. Um, and that can be a little impairment and that can be a a a lot of deficit and chronic kidney disease can come from a lot of different things. Some people are born with certain conditions that make them more likely um, to have kidney disease down the road or something structurally that could be wrong with their kidneys in the US If you are not born with something like that, more people than not have kidney disease as a result of other chronic health conditions, things like diabetes or high blood pressure.

Speaker 3: 14:09

So is it common or is it true that it's like all of our kidneys just kind of decline over the years or is something that you would actually label a kidney disease? How common is that

Speaker 4: 14:19

Now all of us as we get older do lose some kidney function by the time we're nearing the end of our lives. About 37 million people in the US have chronic kidney disease. So that's about one in 10, maybe a little bit more, maybe more like one in nine. That's a lot. It is a lot and a lot of people are at risk even if you don't have chronic kidney disease. Like I said, high blood pressure and diabetes are big risk factors and so the estimate is that one in three people might be at risk for kidney disease even if you don't have any right now. So

Speaker 3: 14:46

You've mentioned diabetes and high blood pressure. Why do those two things among other things lead to a decline in kidney function?

Speaker 4: 14:55

I think with high blood pressure there's a lot of increased pressure and if you recall the , the kidney filters are these clusters of small blood vessels. So if you imagine having higher blood pressure and higher blood pressure over a time, some of those small clusters are going to get damaged . It's almost like putting a fire hose worth of pressure into your garden hose. It's just there's gonna be, you're gonna have some damage at the end of the day.

Speaker 3: 15:19

I like that. I like that metaphor. I'm always striving for metaphors to tell patients 'cause you just talked about a million per kidney, little teeny filtering systems and it's too much pressure. It's just like a pipe with too much pressure in it. So that's high blood pressure. What about diabetes?

Speaker 4: 15:35

Diabetes has a lot of organs that it can affect our hearts and our eyes and our kidneys are no exception. So all of that floating sticky blood sugar tends to get stuck especially in small blood vessels. And so the kidneys again is an organ that is full of small blood vessels just tends to be really impacted particularly when our diabetes is under less tight control as our A one C or our , our blood sugar numbers are higher, the kidneys feel that blood sugar stacking up and stacking up and then what ends up happening is that that filter, that that colander or strainer if you will, starts to get damage . And so more things can fall through it and and in the case of diabetes, protein tends to fall through and that can be something that your primary care doctor or your diabetes doctor is monitoring for If they know you have diabetes, that's one thing every year that they may be monitoring for to watch and see if there's any of those early signs that your kidneys could be involved.

Speaker 3: 16:32

So all you uh, listeners out there, when you go to your primary doctor or any of your doctors um, and they ask you to pee in a cup and you have diabetes, it's 'cause we're looking for your kidney disease before you know you have it because we're looking for that protein. So I'm gonna bring that that question to you then. Okay. So how would someone know they have problems with their kidneys or is it always just found on blood tests ? In other words , um, when should someone you know be worried?

Speaker 4: 16:55

Unfortunately kidney disease is a very silent disease with few exceptions we don't feel our kidneys and we only tend to feel our kidneys when we're passing a kidney stone or sometimes if we have an infection in the kidneys themselves. So most of the time we are finding it with routine blood testing or if you go to the hospital or an urgent care for another issue and you happen to have some blood work drawn. So if you have never had any blood work drawn, it may be helpful to periodically get that done under the supervision of your doctor to make sure that we're not seeing maybe early signs of some kidney disease. And certainly if you have another condition that puts you at higher risk, if you have high blood pressure or you have diabetes, it's very important year over year or even more sometimes to be getting blood work done to catch those early signs of kidney disease.

Speaker 3: 17:43

I get people ask me this question a zillion times, so I'm gonna ask you about creatinine now we're not gonna get into all the details of lab tests, but all the time people are getting a test called their creatinine, that's a blood test for kidney disease. How does that work?

Speaker 4: 17:57

So creatinine is something that our body makes in our muscles. It's, you may have heard of creatine, which people can use when they're trying to lift weights and and bulk up. And so our body cleans up this substance called creatinine and normally if our kidneys are working well we urinate out most of it, we pee it out and so our blood level should be low and everybody's normal can be different when you have a low creatinine number or at least one that's kind of at your level of normal, we can compare that to any changes over time. So if as that creatinine number in your blood builds up, it's a sign that your kidneys are not getting rid of it as well. So higher creatinine often means lower kidney function. Could

Speaker 3: 18:38

You explain for us the difference between chronic kidney disease as we've been discussing and kidney failure?

Speaker 4: 18:45

Absolutely. So chronic kidney disease is viewed on a spectrum. So like we talked about, it's really any impairment in how our kidneys are functioning. And so you can imagine almost like being back in school, you know getting an 80% on a test certainly wasn't a hundred percent but you know it's good enough to pass and that may be very different than getting a 50% or 40%. So as our kidney function is lower and lower, we may be able to do some of the normal jobs but then over time we may start to see some jobs that are not getting done as well. And so we stage or we classify kidney disease in what we call stages one through five and one is pretty mild impairment and five is pretty low kidney function. We're really starting to see symptoms and a lot of um, changes in our blood

Speaker 3: 19:34

Work. You're down to your last few work in nephrons there , the

Speaker 4: 19:36

Last few nephrons , you got 10, you got maybe 10 left, 10

Speaker 3: 19:39

Left of the, of the millions,

Speaker 4: 19:40

You can name all of them.

Speaker 3: 19:41

Yeah. And then you're starting to feel it. There's symptoms then

Speaker 4: 19:43

Correct. When I said you don't feel, you know pain in your kidneys, that really actually goes up until about stage five kidney disease And at that point it's not pain in your kidneys, it's more things you're feeling in the rest of your body as toxins are building up and some of those other substances are just not being handled appropriately. And so when you get to that stage five kidney disease, the difference between that and kidney failure is really your ability to kind of just squeak out the bare minimum number of jobs when you can't do that and you're building up dangerous amounts of blood salts, things like really high potassium or hanging onto so much fluid that it's starting to impact our breathing and you're so full of toxins that you just feel really crummy at that point. People are in kidney failure that things have built to such a critical mass that you really need to do something to do the job of your kidneys, do something to replace them and for most people that's gonna be something like dialysis or getting a kidney transplant.

Speaker 3: 20:42

So chronic kidney disease, is that reversible?

Speaker 4: 20:45

It depends on where you are, are in the stages. I mentioned that we go from stage one to stage five. Unfortunately by the time you're at stage five there's often so much scarring, there's so much damage. It's almost like if you get a cut on your arm, your body makes a scar just to keep two things in place. But there's not a lot you can do to make that go back to normal. And the same is true in the kidneys. Our, our really sweet spot is when you're in an earlier stage, say you're in stage two or stage three , we know that the disease is there and there's a lot more we can do to try to keep it under control and in certain cases we can actually do treatments to cure the kidney disease. I would

Speaker 3: 21:21

Love to have you on a future episode and talk more about things like dialysis and transplant and what's done when your kidneys do pale. We're not gonna have time to do it on this show, but those are successful, right?

Speaker 4: 21:33

They will help do the job of your kidneys. I tell people that something like dialysis isn't going to fix your kidneys but it'll do the job for them like a substitute teacher.

Speaker 3: 21:42

Okay, so that um, a little bit there are some treatments , uh, um, when your kidneys do actually fail. Before I let you go, I'm gonna wrap up the chronic kidney disease section by asking you are there things people can do in their life who either want to prevent kidney disease or maybe have some degree of kidney disease and want and don't want it to be getting worse? Are there things they can do?

Speaker 4: 22:04

Absolutely. I think people ask me all the time, are there things in my diet, are there things in my exercise, are there supplements that I can take? And what I would say is that there's no one diet that's really been proven to be the cure all to prevent or or to treat kidney disease. But most of people, especially people who have kidney disease, they know about should eat a diet that's a little lower in sodium and should eat a diet that's maybe a little bit more plant-based or has a little bit more fruits and vegetables involved often that already has a little less sodium involved as well. So those sorts of healthy eating patterns can be helpful in a general sense, particularly if you have a condition like diabetes or high blood pressure. Your doctors and nutritionists may already be telling you things like avoiding salt and eating a more plant-based almost a , a more diabetic diet. And I think for a lot of us that would be a healthy way to go.

Speaker 3: 22:56

Probably most of us should be doing that anyway.

Speaker 4: 22:58

I tell folks, I think if we all ate a little more like we were diabetic, that would go a long way with a

Speaker 3: 23:01

Lot of us it would be helpful . What about protein in the diet? Is that helpful, harmful, neutral? Pretty

Speaker 4: 23:05

Neutral. Um, there have been some studies that um, even folks who have eaten really low carb, high protein diets, things like the Atkins diet or keto, there hasn't been a lot of evidence that they've been more harmful to the kidneys or that they've really hurt people with kidney disease. Um, I think we eat a lot of protein in the US and so especially as people eat more plant-based diets, it really turns out we actually are getting a , a good amount of protein, at least what we need. And there is some argument when you're getting closer to kidney failure, you're in that stage five kidney disease. Some people go back and forth on maybe scaling back a little on protein at that point. But for most folks, especially if you're being preventative about um, your kidney health, I think not don't have to worry about eating too much or too little protein.

Speaker 3: 23:49

What about other things we ingest? Are there any foods that we should simply avoid or medications that we should simply avoid?

Speaker 4: 23:57

I think there are certainly things that are going to be things we should sort of have caveats about. I talk to a lot of folks who are interested in taking vitamins and supplements and most folks can take those without too much trouble. But there are certain supplements and certain vitamins that have been shown to be harmful for the kidneys to cause injuries to the kidneys or cause almost like allergic reactions in the kidneys. Um, certainly as the internet is more available, people buy supplements online and sometimes we just don't know what's in those, there's not very much regulation And so there can be things like heavy metals or lead or things that really can hurt not only our kidneys but the rest of our bodies. So what I often tell patients is talk to your doctors. Um, your doctors may have some sense of what common supplements and vitamins and herbs might contain, but if you've got questions, certainly bring those products in to make sure that they're gonna be safe and healthy for you, that they don't also break the bank. A lot of these companies can charge you a lot of money for things that may not be doing much or could be hurting you and you also wanna make sure that they're not going to be interacting with any of your other medications to cause you harm or, or to not let those meds do what they need to do.

Speaker 3: 25:03

Jen , if you could leave our listeners with any tips about their kidneys, what would it

Speaker 4: 25:08

Be? I think the best ways we can take care of our kidneys in a general way is to stay hydrated. There's no magic number for cups of water, but drink to thirst and your kidneys are smart and we'll figure out the rest. Taking care of other medical conditions, things like diabetes and high blood pressure putting in the work now and it can be a lot of work to get those under control, but doing that now can really help down the road and prevent other complications like kidney disease and eating a good healthy diet. One that's rich in fruits and vegetables, maybe a little lighter in sodium, I think can go a long way for a lot of

Speaker 3: 25:41

Us. Thank you so much for being on the show today.

Speaker 4: 25:44

Well thanks so much for having me,

Speaker 3: 25:45

Listeners, I hope you've learned something about the kidneys and I wanna thank you all for listening to the podcast here as we wrap up our second season with episode 24. Season three is just around the corner, so I hope you'll join us In the meantime, be healthy and be well.

Speaker 2: 26:02

Thanks for listening to the Healthy Matters podcast with Dr. David Hilden . To find out more about the Healthy Matters podcast or browse the archive, visit healthy matters.org. Got a question or a comment for the show, email us at Healthy matters@hcme.org or call 6 1 2 8 7 3 talk. There's also a link in the show notes. And finally, if you enjoy the show, please leave us a review and share the show with others. The Healthy Matters Podcast is made possible by Hennepin Healthcare in Minneapolis, Minnesota, and engineered and produced by John Lucas At Highball Executive Producers are Jonathan , CTO and Christine Hill . Please remember, we can only give general medical advice during this program and every case is unique. We urge you to consult with your physician if you have a more serious or pressing health concern. Until next time, be healthy and be well.