Does Low GFR Mean CKD in Living Kidney Donors?

[Michael]

The debate of how to assess the health of the remaining kidney of a living donor has been going on for decades, and there doesn't appear to be any signs of resolution. The issue: does a low glomerular filtration rate (GFR) mean you have chronic kidney disease (CKD) if you are a living donor?

The answer matters because being told you have CKD can lead to stress and anxiety, and it can lead to changes in your lifestyle (diet, exercise, etc.) and even to a loss of insurability. The question comes up in the first place because the measures of kidney health used to determine if a patient has CKD are based on individuals with two kidneys. Should those same measures and standards be used for living kidney donors?

The short answer is "we don't know." The medical community so far has been unwilling to publish guidelines for assessing kidney health that are tailored to living donors. That leaves living donors without a clear idea of what some of these kidney health measures like GFR really mean for them.

The purpose of this message is to keep track of discussions of this topic as they occur so we have a place to go to be current on the subject.

[Michael]

Low GFR After Kidney Donation is Not Chronic Kidney Disease
https://atcmeetingabstracts.com/abstract/low-gfr-after-kidney-donation-is-not-chronic-kidney-disease/

Only an abstract of this study is available. They followed a fairly small group of living kidney donors and non-donor patients with chronic kidney disease. They measured kidney health using GFR at the start of the project and again about five years later. The GFR improved for donors and worsened for non-donor CKD patients. They concluded  that "former kidney donors show a substantially different course in kidney function than CKD patients. Even though many kidney donors have a low GFR early post-donation, these healthy individuals should not be regarded as CKD patients. CKD criteria are not suitable for former kidney donors."

(Personally, I would like to see a study with a larger number of participants and a longer period over which the GFRs of donors and non-donors are compared.)

[Michael]

The Unjustified Classification of Kidney Donors as Patients with CKD
https://journals.lww.com/cjasn/pages/articleviewer.aspx?year=2013&issue=08000&article=00019&type=Fulltext#

This articles analyzes several studies of living kidney donors, GFR, and chronic disease that "provides evidence that kidney donors, despite having reduced GFR, are not at increased risk for CKD-associated morbidity and mortality." More specifically, they conclude "kidney donors with low GFR and no other signs of kidney disease should not be classified as having CKD."

This is good news in the sense that a low GFR on its own does not appear to be associated with higher mortality or progression to End Stage Renal Disease (ESRD). But... it leaves open the question of whether there is reason to be concerned if a living kidney donor has BOTH a low GFR and some other sign of kidney disease such as a high level of albuminuria.

The study doesn't come out and say this directly but you could draw these kinds of conclusions:

• Low GFR only (no other signs of kidney disease), you're probably OK.
• Low GFR AND other signs of kidney disease for more than three months, you might have chronic kidney disease.

[Michael]

KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5540357/

Kidney Disease: Improving Global Outcomes (KDIGO) is an independent global nonprofit organization that is "developing and implementing evidence-based clinical practice guidelines in kidney disease." KDIGO published clinical guidelines for diagnosing and managing chronic kidney disease (CKD) in 2012. They published guidelines for the evaluation and care of living kidney donors in 2017.

Chapter 19 of the 2017 living donor guidelines provides suggestions for post-donation care. Section 19.3 addresses living kidney donors who are evaluated using the standard measures (from their 2012 guidelines) and determined to have CKD. The recommendation is to treat the donor as any other patient diagnosed with CKD: "Donors should be monitored for CKD, and those meeting criteria for CKD should be managed according to the 2012 KDIGO CKD Guideline." In other words, KDIGO does not recommend treating living donors differently from people with two kidneys when evaluating and diagnosing CKD.

[Michael]

What Should a Living Kidney Donor Do?

I've seen lots of posts from living donors who were told they have CKD based on the standard GFR chart. It's happened to me. But... I don't think the right response is "you're probably just fine." I think the correct response is "We don't know."

Unfortunately, there aren't standards agreed upon by medical and insurance professionals for evaluating the health of a living donor's remaining kidney, and there are no plans to do so. (I've asked.) So what to do? I think there are three things:

1. Work with your doctor to measure your kidney health year over year to spot any negative trends. Here are specific suggestions, including a worksheet to help with the tracking: PDF version - https://livingdonorsonline.org/worksheets/LivingKidneyDonorHealthTracker.pdf Word version - https://livingdonorsonline.org/worksheets/LivingKidneyDonorHealthTracker.docx


2. Educate your primary care physician. There are peer-evaluated medical papers/commentaries on the topic, a couple of which are posted above.

3. Support legislative protections. Until there are agreed-upon standards for donors, we are at risk of being denied insurance coverage or charged higher rates. Thus, we need the Living Donor Protection Act of 2023 to be passed in this Congress. There are several state initiatives, too.

[Michael]

I would be remiss if I didn't include a link to the classic LDO message thread on this topic started by the incomparable Dr. William Freeman. His first message was posted on March 19, 2011 and it is as relevant today as it was then. (And in some respects speaks to how little progress has been made in 12 years.)

https://livingdonorsonline.org/ldosmf/index.php?topic=141.msg392#msg392

[Michael]

The Consequences of Chronic Kidney Disease Mislabeling in Living Kidney Donors
https://www.mayoclinicproceedings.org/article/S0025-6196(14)00330-9/fulltext


This 2014 article presents two cases of living kidney donors harmed by being characterized as having chronic kidney disease (CKD), despite being in good health. The authors note that mislabeling donors has having CKD can be traced to problems with the current methodology for determining CKD. One problem is that the system does not recognize that "the reduction in GFR associated with unilateral donor nephrectomy is not a progressive disease process and, unlike CKD, is not associated with an increased risk of end-stage renal disease (ESRD), adverse cardiovascular outcomes, or death when compared with the general population," citing five medical research papers to back up the observations about donor health. A second problem is that "the use of GFR estimation equations in living donors frequently results in underestimation of GFR" because the formulas were created to estimate GFR "in a population of binephric [two kidney] patients with true CKD (emphasis added)."

The authors note: "Improved education about the limitations of CKD estimation equations for both physicians and insurance companies may save healthy kidney donors the stress of being mislabeled with a disease. Changes in the CKD classification system itself would be welcome."