[MUSIC PLAYING]

DARRYL CHUTKA: This is Mayo Clinic Talks, a curated weekly podcast for physicians and health care providers. I'm your host, Darryl Chutka, a General Internist at Mayo Clinic in Rochester, Minnesota. Kidney transplants were initially attempted in the early 1950s. However, most of the early transplants failed due to immune system rejection.

Successful transplants were generally limited to those performed in identical twins. With the discovery of immunosuppressant therapy, organ rejection became less of an issue, and successful kidney transplants became quite common. In the US, over 20,000 kidney transplants are performed annually.

So who's a candidate for a kidney transplant? What's the current success rate? And when should a transplant be performed in patients with end-stage renal disease? The topic for today's podcast is kidney transplantation, and our guest is Dr. Carrie Schinstock, a nephrologist from the division of nephrology and hypertension at the Mayo Clinic.

She'll provide answers to these questions and more. Carrie, welcome, and thank you for joining us today.

CARRIE SCHINSTOCK: Well, thank you for having me.

DARRYL CHUTKA: So let's start by asking you, who is a candidate for a kidney transplant?

CARRIE SCHINSTOCK: So at a really basic level, it's anybody who is on dialysis or has end-stage renal disease. That is fairly simple. They could be a potential candidate. If someone is not on dialysis, we start thinking about kidney transplant when the glomerular GFR, or Glomerular Filtration Rate, is less than 25.

That's when we would begin to evaluate them, and they can begin gaining time on a waiting list or get a preemptive transplant, generally when that GFR is less than 20. And it's important to-- it's OK to refer patients early or even if you're a little unsure of whether the patient would meet their criteria for a kidney transplant, because we review all of the cases even before they come here.

And if the patient clearly doesn't meet criteria, we don't think that they would benefit from the transplant even if they're on dialysis. We might decide that it's inappropriate for them to come, and we would relay that information to them. So I think the main thing is anybody on dialysis, they should at least think about it, or if their GFR is less than 20.

DARRYL CHUTKA: And I think early referral can't be emphasized enough. I know the few patients I've had who have undergone a kidney transplant, they really needed time to think about this and accept what's about to be done or considered. And I think it was very helpful for them to meet with the nephrologist early as their kidneys got worse. So is there an age requirement? Is there somebody too young for a kidney transplant?

CARRIE SCHINSTOCK: Not necessarily too young or too old. Now, in pediatric transplantation, the patient has to be a certain size, and that would depend on the donor kidney and different things like that. Generally, about I think two years of age perhaps. But again, it's on a case by case basis, depending on the patient's size.

We get a lot more questions about, can a patient be too old for a kidney transplant? And the answer to that is no. The way I really look at this-- or every case is kidney transplant is a treatment. It's a treatment for kidney disease. And I try to think of, are we going to be able to accomplish those patient's goals with a transplant or with dialysis? Where are we going to better accomplish those goals?

And so even if someone is 75 or 80, if we believe that the benefits of going through transplant outweigh the risk, we think that they would be a good candidate for transplant.

DARRYL CHUTKA: And I imagine an elderly patient who has an otherwise good quality of life would be an excellent candidate.

CARRIE SCHINSTOCK: Yeah, certainly. I mean, obviously, we look at every case individually, and we talk to them you know about the potential risks and benefits, the fact that they would take medications to prevent rejection for the rest of their life. But many people if-- yeah. If they don't have a lot of other comorbidities and they are functional, if they exercise and take good care of themselves and can take care of the organ, it's much better than dialysis.

DARRYL CHUTKA: I believe kidneys were probably the first internal organ transplanted. So you've had a lot of experience with this. What's the success rate currently for kidney transplantation?

CARRIE SCHINSTOCK: So the short-term success of kidney transplant is excellent. So if a patient receives a living donor kidney transplant, about 98% to 99% of those transplants are still going to be working at a year. At five years, about 85% of them are still working. The outcomes after deceased donor kidney transplant-- these are the transplants that come from the waiting list-- are little lower.

But still about 95% to 96% of them are functioning at a year, and about 70% to 75% are functioning at five years. And so the outcomes are very good.

DARRYL CHUTKA: Do transplant kidneys typically have a lifespan or do they continue throughout one's remaining years?

CARRIE SCHINSTOCK: We've seen transplants last a really long time. I don't know the longest transplant that has been functioning from here at Mayo Clinic, but I have seen on occasion patients who received a transplant in the 1960s who are still alive and well with a functioning kidney transplant.

DARRYL CHUTKA: Let's talk a little bit about the benefits of transplantation versus dialysis. I've had patients who have had both, and I think those who have had transplants were quite happy that they did that. But what are the advantages of a transplantation?

CARRIE SCHINSTOCK: One of the main advantages is, in most cases, or in general, for a lot of patients, the survival is better with the kidney transplant rather than remaining on dialysis. Patients simply live longer. To the patient, the big difference is in their quality of life. Dialysis is really onerous.

If they're in in-center dialysis, it's almost a part time job. They go there three times a week for three hours, and then the time to prepare for that dialysis session. And they often even don't feel very well. So it really improves their quality of life from that perspective. Also with kidney transplant, there's not the same dietary restrictions.

So that for patients is a really big deal. And it also gives them the flexibility of travel. So that helps with quality of life. And lastly, especially for young patients, the transplant helps them go back to work, again, because of the huge time commitment in the morbidity that's associated with dialysis.

So the transplant, in general, has not only benefits for longevity or patient survival but many benefits for quality of life.

DARRYL CHUTKA: Mm-hmm. Well, what's the recommended timing for a transplant? Do you prefer that they be on dialysis for a while or would you prefer to get them before they start dialysis?

CARRIE SCHINSTOCK: This is a great question, and probably one of the main points that I'd like to bring up, that it's best if we do a preemptive transplant. And that means it's best if we are able to get the patient to transplant before they start dialysis. It's a myth that someone needs to be on dialysis for some period of time before they receive a transplant.

And this is why it's really helpful if we get that early referral, because it gives us that time to evaluate the patient and make sure that they're ready for the transplant. But there's a lot of benefits to that preemptive transplant. Not only they're able to avoid dialysis, but it's associated with improved patient survival, and also those grafts or kidney transplants from preemptive transplants tend to last longer than if the patient was on dialysis prior to the transplant.

DARRYL CHUTKA: So another reason for early referral to consider a transplant. So where do most kidneys that are transplanted come from? Family members, deceased donors, unknown live transplants? Where do they originate from?

CARRIE SCHINSTOCK: In the country as a whole, the majority of the transplants do come from deceased donors. But here at Mayo Clinic in Rochester, the majority of our transplants traditionally have been from living donors because I think we recognize the benefit of a living donor transplant, and we have a lot of expertise in evaluating and accepting living donors.

But in general, deceased donor's more common. It just may be difficult for people to find that living donor. They just don't know about it. As far as who is the living donor, that can be a family member, a friend, a sibling, many different individuals, more and more commonly that donors are unrelated to the recipient, but it can really essentially be from anyone.

The other point that I want to bring up with that is that, historically, with a living donor, we think that, oh, you need to find a donor who is a relative or you need to find a donor who has the same blood type, and that the recipient was thinking that, oh, I'm blood type O, so I need to find an O donor.

But within the last decade, kidney-pair donation programs have become much more popular. So what are these kidney-pair donation programs? These are essentially programs where we're able to swap kidneys. So we have a pool of donors and recipients who are incompatible on blood type or various other areas of compatibility, and we're able to match donors and recipients in that pool.

So now about 30% of our living donor transplants are through this kidney-pair donation program. So an important point to make is that someone who needs a kidney transplant, they just need to find anyone who is able to be a living donor, and then we work out the logistics of matching or finding the compatible donor for them.

DARRYL CHUTKA: Yeah. That's a very interesting program. I had not heard of that before. Let's talk a little bit about the donors first. Is there anything that would exclude an individual from donating a kidney?

CARRIE SCHINSTOCK: I think some of the major exclusions is if the donor has some kidney disease themselves-- if they have some protein in their urine for example or, in some cases, if they wanted to donate to a sibling, for example, and there's a genetic kidney disease, that would be you know a very strong absolute contraindication, or if the donor has an active psychiatric illness and they're unable to give consent, or if the donor has an active malignancy.

I think more important to discuss is who can be a donor. The donor could have a history of hypertension that is controlled. That's perfectly fine. The donor can have obesity. For certain age groups, the BMI cutoff-- at least at our center-- is up to 40, so that's not an exclusion. The donor could have, especially for older donors, for example, they may have had an isolated history of a kidney stone, for example, and that would be fine.

So in a lot of ways, if a patient is willing to donate a kidney and their health issues are relatively controlled and they do not have any current kidney disease, that they would be a good donor.

DARRYL CHUTKA: You earlier talked about age requirements for the recipient. How about for the donor? Is there an upper age limit where you would not consider them to be a donor?

CARRIE SCHINSTOCK: We don't have any upper age limit. We try to match, if possible, the donor and recipient age. And so if the donor is a more advanced age, optimally, that would be for an older recipient just because the long-term outcomes of a transplant from an older donor may not be as long. But certainly, getting a transplant from an older donor is certainly better than being on dialysis.

DARRYL CHUTKA: Mm-hmm. So what type of evaluation do you do in assessing a potential donor?

CARRIE SCHINSTOCK: It can be very quick. So we can usually do that evaluation within one to two days. That's important. We do a pretty thorough assessment of their blood pressure. So at least here at Mayo Clinic in Rochester-- and actually, at the three Mayo sites-- we do an ambulatory blood pressure, and that's really because we want to make sure that their blood pressure is controlled prior to the donation, whether we need to treat them with medications or something like that.

Obviously, we need to make sure they don't have any kidney disease, and so we do a pretty thorough assessment of their kidney function with 24-hour urine test as well as some more specific ways of measuring their kidney function with an iothalamate clearance. We do imaging of their kidneys. So all of our donors get a CT angiogram.

This is to look at the kidneys themselves. We want to make sure they have two kidneys, but we also want to look at the vasculature for transplant planning. And then, obviously, they'll have you know a set of labs to make sure that there's not any other organ damage. The donor will also have to meet with several individuals.

They'll meet with a social worker, a living donor advocate. The social worker and living donor advocate has a major role to play. We just want to make sure that the donor isn't coerced and they don't have any uncontrolled psychiatric illness, for example. They're going to meet the surgeon, the nephrologist, and sometimes they'll meet with a nutritionist or even a pharmacist if they need to in their particular situation.

DARRYL CHUTKA: So quite an involved process. So I'm sure there have been outcome studies done on donors. Do they typically do as well as an individual who has two kidneys? Is their lifespan any different?

CARRIE SCHINSTOCK: In general, their lifespan is no different. Now, as far as the donor's risk of kidney disease-- if you look at the donor's risk of kidney disease compared to the general population, the donor is actually less likely to develop kidney disease. But that's not a really fair comparison because people who are healthy enough to be a kidney donor are healthier than the general population.

But when we compare two individuals who are equally healthy, those who donate a kidney are at slightly higher risk of developing kidney disease long term, but that risk is extremely small. That's why they undergo a really thorough evaluation, because we want to just minimize that risk.

Because there is that small risk and this is a surgery that they don't need-- but we recognize the benefits to the donors, especially if they're donating to a family member or someone close to them. This sometimes is really helpful to their whole unit or to their lifestyle. It does provide benefit to them.

DARRYL CHUTKA: Mm-hmm. What's the typical waiting period once you've decided a patient is a candidate for a kidney transplant? What's the waiting period like?

CARRIE SCHINSTOCK: Now, as far as if they have a living donor, there isn't going to be any waiting period other than what it would take to get the recipient evaluated and the donor evaluated. We're able to schedule the transplant pretty quickly. For deceased donors, the average wait time is about five years. Here in Minnesota, the waiting times vary across the country and depending on the region the patient is listed at.

DARRYL CHUTKA: So is this waiting list a state list? Is there a national registry or is it each institution have its own waiting list? How is that determined?

CARRIE SCHINSTOCK: That's a good question. I think people envision this long waiting list and they're really looking for their number. It's not really like that. So there is this national waiting list, but the US is also divided in various regions. The allocation system is quite complex. What they really try to do is match the kidney to the recipient based on how difficult that recipient is to match and how long they think that recipient is going to live or they estimate that recipient is going to live.

But in short, the kidney is first allocated regionally. If they're able to find that appropriate recipient in the region, that's where it will be allocated. But in some cases, the kidneys are allocated nationally. There's this organ shortage, and there's this desire to use as many organs as possible to eliminate discards.

And so if there are organs that, for instance, a particular region might not use, for example, they might be shipped to a different area of country where they would be used.

DARRYL CHUTKA: So this may be a silly question, but I was curious. When a patient receives a kidney transplant, does this replace a kidney? Do you take one or both of them out or you just leave them in place?

CARRIE SCHINSTOCK: There-- a great question that-- we get asked that all the time.

DARRYL CHUTKA: OK. I thought I would save that.

CARRIE SCHINSTOCK: No, it's probably one of the more common questions that we get. We usually leave the old kidneys in place, and the new kidney transplants usually in the right lower quadrant. Sometimes on the left, but usually in the right. So a completely different place. The only exception to that would be if the old kidneys are causing problems.

So a good example of that is if somebody has polycystic kidney disease, for example, where the kidneys are really large and they're painful or they're having blood in their urine, for example. We can take out those polycystic kidneys at the time of the kidney transplant. And that's actually a unique feature of our program that we can do both at the same time.

DARRYL CHUTKA: OK. And one last question. Any ethical issues surrounding kidney transplants?

CARRIE SCHINSTOCK: I think in the current era, there's not many ethical issues. I think the main thing is that the sale of organs is prohibitive. So part of the living donor evaluation is just to make sure that the donor is not being paid in any way or is not getting any kind of secondary gain.

DARRYL CHUTKA: OK. Well, Carrie, you've given us some interesting thought. Can you give us maybe two or three key points that summarize our discussion on kidney transplants?

CARRIE SCHINSTOCK: Well, I think number one, kidney transplant is the optimal treatment for end-stage renal disease. People can be at almost any age. And it's best if they're able to get that kidney transplant before starting on dialysis, so it's a preemptive transplant. And even better if they're able to get a preemptive living donor transplant, because that living donor transplant and also the preemptive transplant is associated with improved outcomes.

DARRYL CHUTKA: Well, we've been discussing kidney transplantation with Dr. Carrie Schinstock, a nephrologist at the Mayo Clinic. Carrie, thank you for sharing your knowledge with us. I learned some things I had not heard before. So thanks very much for joining us.

CARRIE SCHINSTOCK: Thank you for having me.

DARRYL CHUTKA: You can now listen to over 100 different medical topics developed for primary care providers on Mayo Clinic Talks podcasts. Find them at ce.mayo.edu or your favorite podcasting app. If you've enjoyed Mayo Clinic Talks podcasts, please follow us. Stay healthy, and see you next week.

[MUSIC PLAYING]