By Stephen Z. Fadem, MD, FACP, FASN
This is a summary of the article “The role of serum phosphate control in supporting transplant readiness in patients on dialysis,” authored by Laura A. Williams, MD and me in August 2025.(1) It explains why keeping blood phosphate levels in a healthy range is important for people on dialysis who hope to receive a kidney transplant, and how better phosphate control may help patients qualify for transplant and do better afterward. Readers can access the original article at https://bit.ly/4rWtRL7.
Kidney disease and transplant
Chronic kidney disease (CKD) affects around 10 to 12% of the population, and some may progress to end-stage kidney disease, where the kidneys no longer work well enough on their own. At that point, treatment options are dialysis or a kidney transplant, and a transplant usually offers longer life, better quality of life, and lower overall medical costs than staying on dialysis. Because donor kidneys are limited and many patients are waiting, anything that improves “transplant readiness” is important.
What is “transplant readiness”?
The American Association of Kidney Patients (AAKP) defines “transplant readiness” as a patient’s opportunity and ability to pursue kidney transplantation when it aligns with their aspirations and goals of care, not simply whether they meet a clinic’s medical checklist.
It is fundamentally about care choice, access to FDA-approved treatments, and empowerment, and includes the following elements:
• Understanding all kidney replacement therapies.
• Removal of barriers to access all safe and effective FDA-approved treatments, as decided by the patient in consultation of the doctor(s) they choose to care for them, that support an individual’s ability to remain healthy to receive a transplant.
• Alignment with a patient’s life goals and aspirations as they define it.
• Empowerment through education and respect for autonomy.
What phosphate is and why it rises
Phosphate is a mineral found in many foods that helps build bones and supports many body functions. Healthy kidneys remove excess phosphate from the blood, but when kidneys fail, phosphate builds up (hyperphosphatemia), even on dialysis. This buildup can lead to problems with bones, blood vessels, heart health, and hormone levels.
How high serum phosphate harms the body
When phosphate is too high, it can pull calcium out of bones, weaken them, and increase the risk of fractures. At the same time, high phosphate, and calcium can deposit in blood vessel walls and heart tissue, causing “hardening of the arteries,” high blood pressure, heart strain, and a higher risk of heart attack and stroke. High phosphate levels stimulate a hormone that helps regulate them. This is known as FGF-23, which can be toxic to patients with kidney disease. Not only that, but FGF-23 suppresses Klotho, an important hormone that helps protect blood vessels from becoming damaged. For people on dialysis, heart and blood vessel disease is the leading cause of death, and high phosphate is a major, changeable risk factor for these problems.
Why phosphate matters for transplant
Studies show that people who go into transplant surgery with very high phosphate levels have higher chances of delayed kidney function right after surgery and a higher risk of losing the transplanted kidney over time. Lower, well-controlled phosphate levels before transplant are linked with better graft (kidney) survival and better overall outcomes after surgery. Many transplant centers look at phosphate as one sign of how well a patient is managing their health and how ready they are for a transplant, even if a normal phosphate level is not an official requirement.
Transplant readiness and fairness
“Transplant readiness” includes medical factors like heart health, infections, phosphate and other labs, and practical factors such as being able to follow treatment plans and attend appointments. Because lab results such as phosphate levels can be affected by access to healthy food, medications, and medical care, using them in transplant decisions can sometimes worsen existing inequalities if not handled carefully. The authors argue that tracking wait-list times, transplant rates, and posttransplant results by phosphate levels, and by type of phosphate-lowering treatment could help make decisions more transparent and fairer.
How phosphate is managed now
Standard tools to lower phosphate include dietary changes, such as limiting processed foods and certain high-phosphate foods, and phosphate binder pills that are taken with meals that trap phosphate in the gut, so it is not absorbed. Even with these approaches, a large share of dialysis patients still have phosphate above target levels, often because of high pill burden, side effects, and the challenge of following strict diet and fluid limits. Newer treatments that block phosphate absorption in the intestine, along with medicines that control parathyroid hormone and possibly vitamin K2 to protect blood vessels, may offer additional help, though more research is needed.
What this means for patients
For a person on dialysis hoping for a transplant, controlling phosphate should be viewed as part of preparing the body for a new kidney, not just “fixing a lab number.” Better phosphate control may shorten waiting time on dialysis therapy, support stronger bones and healthier blood vessels, improve the chances that a transplant center will consider a patient ready, and help the transplanted kidney work better and last longer. Expanding access to effective phosphate-lowering options and tracking their impact on transplant access and outcomes may improve patient outcomes and reduce overall care costs.
Dr. Fadem is a champion for chronic kidney disease education. He is a Clinical Professor of Medicine, Baylor College of Medicine, Section of Nephrology. Dr. Fadem attended Tulane University and graduated from the University of Oklahoma College of Medicine. After he completed his internship and residency at the University of Texas Health Science Center – MD Anderson and Hermann Hospitals, he did a renal fellowship at the University of Texas Health Science Center, San Antonio. Dr. Fadem was one of the first doctors to discover the value of the Internet for patient education, and founded several websites dedicated to public service and the dissemination of clinical information, including The Nephron Information Center, Wikikidney, Touchcalc, renalworld.com, and dialysisunits.com. He has participated heavily in the development and revisions of numerous AAKP patient education materials, including the AAKP Patient Plan series and the AAKP Kidney Beginnings: A Patient’s Guide to Living with Reduced Kidney Function.
Dr. Fadem is the recipient of the National Kidney Foundation’s Distinguished Service Award, the AAKP Visionary Award, the AAKP Peter Lundin, MD Award, the AAKP Medal of Excellence and the President’s Volunteer Service Award. Dr Fadem is listed in America’s Top Doctors. He serves as editor of aakpRENALIFE magazine, and as historian for AAKP.
Disclosure
Dr. Fadem has served as a principal investigator for Ardelyx, Inc.
1. Williams LA, Fadem SZ. The role of serum phosphate control in supporting transplant readiness in
patients on dialysis. Curr Med Res Opin. 2025;41(9):1665–8.
