Dr. Ron Falk invites Dr. Emily Chang, a kidney doctor with the University of North Carolina who cares for patients with PKD, to be a guest on the Chair’s Corner. They discuss symptoms, diagnosis, impact on welling, autosomal recessive vs autosomal dominant, and more.
Dr. Chang is the co-director of the Polycystic Kidney Disease Center, which is a center of excellence, and is also an associate professor. Her research uses ultrasound and other biotechnologies to improve the care of patients who have diseases of the kidneys.
Topics Covered
00:00- 01:40
FALK: Today, we invite Dr. Emily Chang, who is an associate professor of medicine in the UNC Division of Nephrology and Hypertension. She is here today to help inform us about a condition called polycystic kidney disease. And we’ll let her abbreviate that when she starts talking with us. Dr. Chang is the co-director of the Polycystic Kidney Disease Center, and that is a center of excellence here at UNC. It provides specialized services for patients with polycystic kidney disease. And her research includes the application of how to view the cysts, the polycystic kidney disease, with a technique called ultrasound and other newer biotechnologies that improve the care of patients who have this kind of kidney disease and kidney disease in general. Dr. Chang also cares for patients who have chronic kidney disease with a specific focus on helping patients manage their day-to-day conditions through lifestyle, diet and medication changes. So, Dr. Chang, welcome to the podcast.
CHANG: Why, thank you so much for having me.
01:41- 04:25
FALK: Help us understand what polycystic kidney disease is. What are those words?
CHANG: The disease really, it comes right from the name. So, if you think about it, poly means many, cystic for cyst in the kidney. So many cysts in the kidneys. The disease is exactly described by the name.
FALK: I don’t understand what a cyst is?
CHANG: Cyst is like a bubble is probably the easiest way to describe it.
FALK: It’s fluid filled?
CHANG: It can be fluid filled. It can sometimes you can have bleeding into it. Sometimes you can just have debris that falls into it. But it’s basically fluid filled of different types.
FALK: So, patients have two kidneys. And are these cysts in both kidneys or just one?
CHANG: Typical polycystic kidney disease involves cysts in both kidneys. Although there are atypical forms of the inherited disorder.
FALK: So how many cysts would you find in a patient or in one kidney of a patient with polycystic kidney disease?
CHANG: Oftentimes it’s what we call innumerable, too many to count. So, you can’t even really put a number on it. Early on in the disease sometimes you can count them and there are criteria for figuring out if we think a patient has the inherited, inherited polycystic kidney disease.
FALK: So, we’ll get into the inheritance in a minute. But I’m trying to make sure we all understand the cysts themselves. Do they hurt?
CHANG: They can hurt. So, the pain that comes with polycystic kidney disease actually comes from growth of the kidneys. And they grow so much that they make the capsule expand the capsule that surrounds the kidneys expand. So typically you’ll see pain with larger kidneys, but it doesn’t always correlate. So sometimes I’ll have patients with very large kidneys who tell me they don’t have pain. But in general, the larger the kidney, the more likely you are to have pain.
FALK: So kidneys are usually and we’re in the metric system. They’re 9 to 10, 11 centimeters in length, smaller. If your smaller person larger. If you’re a larger person, how big do the kidneys of patients with polycystic kidney disease get?
CHANG: The 9 to 11 is about the size of the fist, so you can think about it on average, the size of a fist. Polycystic kidney disease can get upwards of 20 centimeters long. So that’s at least double. I’ve seen ones that are three times that. So they can get quite large in patients with very large kidneys. You can even palpate. You can feel the kidneys if you feel in the right place.
04:26- 07:15
FALK: So it’s interesting, though, that patients don’t feel this happening until I guess the kidneys have so many cysts that they stretch the capsule. Is that right?
CHANG: Yes, that is correct. A lot of times patients present with no symptoms. Probably the most common presenting symptoms is just elevated blood pressure. And your doctor is investigating why your blood pressure’s elevated in a person that’s young who has no other reasons for it, they may present with blood in the urine, and that’s not explained.
But a lot of times it’s not pain. And then it’s found, incidentally.
FALK: And if there is pain. Kidneys are located in the back. So it’s really in your flank. It’s always interesting when people come and say, I’m having kidney pain and their pain. They have their hands on the on the front part of their abdomen or their belly. And really, you want them to put their hands where, where is flank pain?
CHANG: in your lower back above your hip hips and pelvis, but your lower back.
FALK: And if there’s pain, it could be on one side. Or is it always both sides or can it be one side?
CHANG: It can be one side. It can be both sides. And lots different things can cause this kidney pain. My chronic kidney disease patients, not my polycystic kidney patients, think that kidney disease itself can cause pain. So I often have to clarify for them that chronic kidney disease doesn’t cause pain. But in patients with polycystic kidney disease, I definitely am worried about whether it’s growth of the kidneys or other things that can cause kidney pain like cyst rupture, infection and kidney stones.
FALK: So kidney disease in general is a silent disease. You can have substantial damage to the kidney from any cause, and you just don’t feel it. We, as kidney doctors, would love the kidneys to scream because then we could pick up disease early. That said, so, theses ruptures that right, they can pop?
CHANG: they can rupture, and that often leads to acute pain. So sudden pain, which is different from the chronic kind of ongoing pain that some of our polycystic kidney disease patients feel.
FALK: And then with they see blood in their urine or?
CHANG: they might, they might see blood in their urine, it might be a sudden blood in the urine along with the pain. And usually that’s one side.
FALK: And they also the cysts can get infected.
CHANG: Also the cysts can also get infected, which can cause a lot of pain too.
FALK: If a person has an infected cyst, what do they do about it?
CHANG: Well, they should get treated with antibiotics, but it is important to make sure that in a for allergist is involved in the care the choice of antibiotics because there are certain antibiotics that can penetrate the cysts where others cannot.
07:16- 09:09
FALK: You started out by using the word inherited. So there are forms of forms of cystic disease in which there are family members that have the disease, and then there forms of cystic disease in which there’s no clear inherited pattern. So let’s dive into that because if I’m a patient, I’m of course worried about are my kids going to get it? Did my parents have it and not know about it? Help us understand the two different types of polycystic kidney disease. There are words autosomal dominant, autosomal recessive. Help, help, help. What do those words mean and how do you figure this out?
CHANG: So before we even get to the inherited, I want to start by saying that there are actually a lot of people who have cysts in their kidneys, and that is not uncommon.
And so just because you see the word cysts, kidney on your report, your imaging report, it doesn’t mean you have polycystic kidney disease. And you can have multiple ones on both sides and not have polycystic kidney disease.
FALK: That’s really an important point because there’s so many patients that get screening, ultrasounds or CP’s or other imaging studies and they are told they have a cyst with nothing in that cyst other than fluid and they shouldn’t immediately jump then to saying, no, no, this is polycystic kidney disease, it’s an isolated cyst or two or three or many.
CHANG: That is absolutely correct. And it’s not even just the patients, people who aren’t thinking about this all the time get this confused and don’t understand that some of these are not concerning, and sometimes it does take a nephrologist or a urologist to look at them and decide what’s concerning.
09:10- 12:35
FALK: So let’s come back to this inherited two different entities. What’s autosomal dominant and what is autosomal recessive?
CHANG: So I’ll start with the autosomal recessive. Autosomal recessive is when there is a recessive gene present in both the parents that the child inherits. There’s a one in four chance they will get it. It is much more severe and much less common than the autosomal dominant. It’s usually picked up prenatally just on routine ultrasound and imaging of the fetus. So often when the child is born, it is known that they have autosomal recessive, polycystic kidney disease, and this is a challenging disease to treat a lot of times, the most of the time. By the time they reach adulthood, their kidneys are already impacted. And because of the severity of this disease, I actually have not treated anyone with autosomal recessive polycystic kidney disease.
FALK: So by recessive, it also can skip generations.
CHANG: That’s correct.
FALK: And it’s uncommon. How uncommon is it?
CHANG: One in 20,000.
FALK: So. that’s really not a common disease at all.
CHANG: Not a common disease at all. And if you compare it to autosomal dominant polycystic kidney disease that’s in 1 in 400 to 1 in 1000. So that is the most common inherited kidney disease that there is.
Falk: So tell us what autosomal dominant means
CHANG: In that case, the gene that is inherited is dominant, meaning you only need to have one of them. And so this does not skip a generation. And although sometimes it can skip if, if a disease is so mild that you don’t pick it up, but the disease has to have been present in every generation to be passed down.
FALK: And there are specific genes associated with this with both, but also autosomal dominant. What are those genes?
Chang: There are two main genes that account for most of the autosomal dominant polycystic kidney disease PKD-1 and PKD-2. There are a lot of other genes that contribute to it as well, but those are the main ones. And most people will have a defect in one or the other and patients who have defects in PKD-1 one typically have a more severe disease that occurs earlier in life.
Falk: So these are genetic diseases, and we know the genes. How come there’s so much variability, when do patients figure out they have this disease?
Chang: Yeah, that is a great question. And even within the same family where there are the same genes inherited, you see a lot of variability and it’s a pretty complicated answer has to do with the, the cells in the patient that get expressed and how much of it gets expressed and probably things we really don’t even understand. But the reason that people don’t get detected till later in life is because it is silent. There isn’t really symptoms until the disease gets pretty advanced and unless you had imaging done for some other reason and it was picked up, incidentally, a lot of people don’t get detected until late there.
FALK: Certainly, if you knew that your parents had it, then you would be more alert to the chances that you would get it.
CHANG: Absolutely.
12:36- 13:55
FALK: Dr. Chang, you’ve described the variability in the presentation, how people figure out they’ve got the disease in the first place. It’s usually picked up on an imaging study and you’ve done a lot with ultrasound and other kinds of kidney imaging. Tell us what you see then on this imaging study.
CHANG: So you can do imaging. There’s lots of different kinds of imaging you can do to evaluate polycystic kidneys, including ultrasound, CT and MRI, and they’re really quite fascinating to look at. If you look at images a lot, they’re quite large, as we’ve already talked about. And ultrasound, of course, of use, as you’ve mentioned, is my baby. I love ultrasound. And the interesting thing about ultrasound and polycystic kidneys is that sometimes the kidneys get so large you can’t even see the whole kidney in one field.
And so you have to get multiple slices across to get the entire kidney because they can be so large, because they can be so large.
FALK: And when you’re scanning around or looking by CT, sometimes you see cysts not just in kidneys, but you can see them ..?
CHANG: In the liver is the most common second place to see cysts. 85% of patients by the age of 30 have liver cysts present too.
13:56-16:15
FALK: And you can have cysts or other things, other parts of the body that are affected the heart, the pancreas, the brain. And we can get into more of that for a moment. But from your perspective, taking care of a lot of patients with this disease, what do you look out for? What are you watching?
CHANG: The number one thing that I’m looking for is their risk of progression, because their question to me is, are my kidneys going to fail? Especially if they had a parent that had kidney failure and ended up on dialysis or needed a transplant. They also want to know, is that going to happen to me? So that’s a place where imaging comes into big play and potentially genetic testing because we have risk calculators that can help us predict the time until kidney failure and that can help us make some decisions that can inform the patient so they know what their risk is. So that’s number one. The other thing that we really pay attention to is complications in the kidney and beyond. So things like rupture, pain, infections, stones…
FALK: rupture of cysts,
CHANG: rupture of cysts. and then these things that happen outside the kidneys, because there are some serious things that can happen outside the kidneys and we want to be aware of them as soon as possible so we can treat them. And lastly, one other thing that is often forgotten is the emotional toll that this plays on the patients, because, you know, we think a lot about the numbers and the size and the pain, but it really, because it’s a genetic disease, it burdens a lot of patients. And am I going to pass it on to my children? Should I have children? How do I do this? And, and that is something that often goes overlooked.
FALK: And part of that emotional toll for a parent is, my goodness, I’ve got this disease. I didn’t know my parents had it and should I have my children screened? That’s a complicated question all by itself.
CHANG: Yes, that is a very complicated question. And that’s one reason why I’m so thankful to our colleagues in genetics medicine, because they help us navigate through these questions for the patients.
16:16- 22:43
FALK: The life expectancy of patients is incredibly variable from 50 some years to 70 some years. You can, you can die with your polycystic kidney disease rather than of it. Or you can, as you describe, progressed on to end stage kidney disease requiring a transplant, for example. Are there ways of preventing that process where polycystic kidney disease leads to kidney failure?
CHANG: Yes. Thank you for that question. There is actually one treatment that we have available. And again, this is a reason why it’s really important to see your nephrologist or kidney doctor to have a discussion about whether that treatment is right for you. It’s not the easiest treatment. It’s not hard, but it’s not easy. And there are things that need to be understood about it before embarking on it.
FALK: What’s the name of that treatment?
CHANG; It’s called Tolvaptan.
FALK: And what is that drug?
CHANG: It is a medicine that blocks ADH so that the cysts don’t grow. ADH is a hormone that’s released that causes the cysts to grow over time, and if you block it, then it’s been shown that the cysts grow slower and you reach end stage kidney disease later. The problem is that this medicine also makes you pee a lot.
FALK: All the time.
CHANG: Which is perfectly tolerable for some patients. Some patients I’ve had have no problems with it, like just no problem at all. Some patients, it’s intolerable. Sometimes it has to do with the job and whether their employer allows them to take frequent restroom breaks. But that’s the main side effect.
FALK: And of course, there are the usual ways of general health care. Keep your blood pressure under good control. Make sure you have increased physical activity.
CHANG: Yes.
FALK: Diet. You want to talk about diet for a moment?
CHANG: Well, I want to talk about the blood pressure and really emphasize that because the point there is that we want to reduce any other risk factors that can make your kidneys get worse. And blood pressure is absolutely critical. And in fact, we aim for lower blood pressures in our patients with polycystic kidney disease who are younger and on the healthier side, which is true for a lot of our polycystic kidney disease patients, because we are really trying to prevent the impact of blood pressure later on in life. It is also important in your diet to drink lots and lots of water if you have polycystic kidney disease. There is some thought that that helps suppress the ADH as well so the cysts can grow slower. That’s not entirely clear. But drinking a lot of water is important for the kidneys. And then diet wise, the most important thing I would say is sodium restriction and trying not to use too much sodium, trying to limit your processed foods and your fast food intake
FALK: Try to avoid salt at all costs. I hate salt. Let me ask, this drug Tolvaptan is a complicated drug to use. So, if you’re a patient with polycystic kidney disease and you’re not on that drug, how do you get help?
CHANG: You need a nephrologist. That’s the best way to get help, to get figure out, first of all, if you need the drug. And secondly, to help you get on it, because it’s not a simple process that typically takes a primary care physician referring you to a kidney specialist.
And ideally a kidney specialist that deals in this regularly because there are lots of nuances of how to manage it and handle it, that it’s really better if you have experience in this area
FALK: And you’re the director actually of a Center for Excellence that deals with polycystic kidney disease because of the number of people that you care for.
CHANG: That’s correct. My wonderful colleague, Dr. Evan Zeitler, has also gone down this path with me. He also treats chronic kidney disease. And we share a lot of common beliefs about treatment and treatment style. And so we were a natural fit and we’ve really enjoyed working together so far on this project.
FALK: One other issue that I think we need to talk about is that some patients with polycystic kidney disease can develop aneurysms or enlargement of blood vessels in their brain and those aneurysms can rupture. And that’s always a fear. Part of this emotional toll of patients. What are your suggestions for patients in terms of screening and care for that potentially deadly consequence?
CHANG: If you have a family history of aneurysm or a suspected aneurysm, I do think it’s reasonable to have at least one screening imaging test of your brain. After that, I recommend to patients if they have symptoms, meaning change in vision, new onset, sharp headache that would suggest that there may be something going on in the brain.
Then I would re-image them.
FALK: Moving forward, looking into the future, what other kinds of options are patients going to have?
CHANG: That is a question. Very good question. And there are lots of drugs being looked at to see whether they can help patients with polycystic kidney disease. And unfortunately, at this point, the only trials are in phase one, meaning very early. So there is nothing that’s right up on about to be released. There are studies looking at what’s called repurposing of other medications to see if they can also prevent progression of kidney disease.
So these things are on the horizon, but nothing is right. They’re available. This is another reason I think it’s good to be seen by a nephrologist who has experience in this area, because when there are clinical trials that become available at centers like ours that are center of excellence, we will have exposure to those trials more quickly.
22:44- 25:28
FALK: There’s also a wonderful resource called the Polycystic Kidney Disease Foundation, the PKD Foundation, that has lots of information for patients and also can help steer you as a patient to a place that’s close to you that specializes in this disease.
CHANG: Yes, the PKD Foundation of Excellence is excellent, and that is who kind of sponsors the different centers of excellence. And they’ve really done a lot to move this field forward. And what you said is exactly right. Once we got our designation, we actually did have a patient in North Carolina reach out to the foundation who hooked him up with me.
He’s unable to travel to come here to see me. But we talked a lot on the phone about what can be done locally and how to help him.
FALK: Talk to us about the other providers, because there are other people who are really instrumental in helping with these patients.
CHANG: That’s correct. At all the Centers of Excellence one of the things that is crucial to our success is having a network of providers in other specialties that are needed frequently by these patients. For instance, our urology colleagues are interventional radiology colleagues, our pain management colleagues, genetics, medicine, hepatology, all of these fields really come into play for certain patients that have certain issues. And since we became a center of excellence, I’ve gotten so much more familiar with my colleagues in these other fields who treat this disease, and they really do have a specialty.
So it’s useful to be treated as a Center of Excellence where your nephrologists can know who may be able to help your specific issue.
FALK: It’s also good to have local support wherever you are. Support from your primary care doctor, support from family members, suzepport from other patients who are going through exactly the same process that you are. It’s always nice to hear how they’ve managed to win their way through determining how best to live with this disease in the most comfortable, easy, nontoxic way possible.
FALK: Dr. Chang, thank you so much for spending time with us and sharing your wonderful expertise. It’s really a pleasure to have you on this podcast.
CHANG: Thanks. Thank you so much for having me. I really enjoyed it.
FALK: Remember, you are not alone on your health journey. Stay informed, stay proactive and together as a community, we can make a positive difference in managing your health and well-being. Thanks so much for joining us. Until next time, take care.