Glossary

Anti-rejection medications: A type of drug given to transplant recipients to prevent their immune system from attacking the transplanted organ. These medications help reduce the risk of organ rejection and are usually taken for the lifetime of the transplant. See also immunosuppression.

Calculated panel reactive antibody (cPRA): A measurement used to determine how sensitized a kidney transplant patient is to potential donors. It estimates the percentage of donors against whom the patient has preexisting antibodies. A higher CPRA indicates greater sensitization, making it more difficult to find a compatible kidney and increasing the risk of rejection.

Champion: Someone who helps a kidney patient by spreading the word about their need for a donor.

Chronic kidney disease (CKD): A long-term condition in which the kidneys gradually lose their ability to filter waste and excess fluids from the blood, typically persisting for at least three months and often progressing over time. 

Compatibility (match): The biological suitability between a donor and recipient, which helps reduce the risk of rejection after kidney transplantation. Compatibility is measured through blood type, crossmatching, HLA tissue typing, and eplet matching.

Creatinine: A waste product produced by muscles from the breakdown of a compound called creatine, which is filtered out of the blood by the kidneys and excreted in urine. High levels of creatinine in the blood often indicate that the kidneys are not working properly.

Crossmatching: A critical blood test performed immediately before transplant surgery to determine if a recipient’s antibodies will attack the donor kidney. A negative result means no reaction (successful match), while a positive result indicates a high risk of rejection.

de novo DSA: New, harmful antibodies developed by a transplant recipient against their transplanted organ’s HLA proteins, appearing weeks, months, or years after surgery. Unlike preformed antibodies, de novo DSA emerge later, often signifying chronic rejection, immune damage, and increased risk of graft loss. 

Dialysis: The most common treatment for kidney failure, typically required when patients have reached Stage 5 of chronic kidney disease. Dialysis acts as an artificial kidney, filtering waste and excess fluid from the patient’s blood. There are two main types: hemodialysis and peritoneal dialysis.

Directed donation/direct donation: A type of donation where the donor donates directly to their intended recipient.

Donor mentors: A free, voluntary program offered by the NKR that allows potential donors to speak to someone who has already gone through the living kidney donation process. Donor mentors share their personal donation experiences, provide guidance, answer questions, and help educate candidates about the donor process.

Donor search coach (also microsite coach): Someone who has found themselves or a loved one a kidney through a donor search, and offers guidance and support to microsite patients who are searching for a living donor.

Donor Shield: A comprehensive suite of support and protections offered to living kidney and liver donors by the NKR. It includes financial assistance for donation-related lost wages and expenses, as well as a wide range of help before, during, and after donation to make the donation process as easy, convenient, and safe as possible.

Donor-specific antibodies (DSA): Antibodies produced by a transplant recipient’s immune system that specifically target the HLA of a donor organ. The presence of DSA increases the risk of antibody-mediated rejection and can affect the long-term survival of the transplanted organ.

End-stage renal disease (ESRD) (also end-stage kidney disease, ESKD): The most advanced stage of chronic kidney disease, in which the kidneys have permanently lost nearly all ability to function (typically defined as kidney function below 10%–15%), requiring dialysis or a kidney transplant to sustain life.

Eplet: A tiny cluster of polymorphic amino acids on the surface of HLA molecules, acting as the minimal functional unit recognized by antibodies. Matching eplets between donor and recipient can reduce the risk of rejection and help predict long-term transplant outcomes.

Eplet matching: A process that allows kidney donors and patients to be compared at the molecular level, focusing on eplets. The closer the match (fewer eplet mismatches), the lower the likelihood that the recipient’s immune system will recognize the donor organ as foreign and produce antibodies against it. This approach helps transplant teams select kidneys that are more likely to be accepted by the body and function well over time.

Eplet mismatch: The difference between the eplets of a donor and a recipient. The best possible match is a zero eplet mismatch, meaning the eplets of the donor and the recipient are an exact match.

Family Voucher Program: An NKR program that allows living kidney donors to donate to a stranger on the waitlist while protecting their family members in case they ever need a transplant. The donor can name up to five family members or friends as family voucher holders. Only one voucher can be redeemed. Vouchers are non-transferable and never expire. 

Glomerular filtration rate (GFR): Measures how well the kidneys filter blood. A normal rate for adults is 90–120 mL/min/1.73, while under 60 mL/min/1.73 indicates kidney disease and below 15 mL/min/1.73 indicates kidney failure.

Glomerulonephritis: A serious kidney disease characterized by inflammation of the glomeruli—the tiny, filtering units that remove waste and excess fluids from the blood. This allows blood and protein to leak into urine, often causing high blood pressure, swelling (edema), and potential kidney failure if untreated. 

Graft: In a kidney transplant, the graft is the donated healthy kidney surgically placed into a recipient with kidney failure to restore function.

Hemodialysis: A type of dialysis in which a machine filters waste products, excess fluids, and toxins from the blood when the kidneys are no longer able to do so effectively. Blood is removed from the body through a vascular access (such as a fistula, graft, or catheter), passed through a dialyzer (artificial kidney) where it is cleaned, and then returned to the body. It is usually performed several times a week at a dialysis center.

Human leukocyte antigen (HLA): A group of proteins found on the surface of most cells in the body that help the immune system recognize which cells belong in the body and which are foreign.

HLA matching (also antigen matching): The process of comparing the HLA of a donor and a recipient to determine compatibility for organ or tissue transplantation. The closer the match, the lower the risk that the recipient’s immune system will see the transplanted organ as foreign and attack it, which reduces the risk of rejection and improves transplant outcomes. HLA matching has been the standard for determining donor–recipient compatibility for many years, but now there is an improved, more granular method, called eplet matching.

ImmunoFree: A company founded in 2023 to improve the lives of transplant patients by using new stem cell technology to eliminate the need for immunosuppressive medications.

Immunosuppression: The reduction or inhibition of the body’s immune system, resulting in a weakened ability to fight infections and diseases. In the case of kidney transplants, immunosuppression is deliberately induced using immunosuppressive medications to prevent the body from attacking the kidney, leading to organ rejection.

Intended recipient: The person a donor wants to help through their kidney donation, either by receiving the donated kidney directly or by receiving a voucher for a future living donor transplant.

Kidney failure (also renal failure): A condition in which the kidneys lose the ability to filter waste products and excess fluids from the blood, leading to a buildup of toxins in the body. It can be acute (sudden) or chronic (long-term) and may require dialysis or a transplant in severe cases.

Kidney for Life: An NKR initiative that uses advanced DNA sequencing technology to analyze the biological match between kidney transplant recipients and living kidney donors. This helps ensure the best possible match so the transplanted kidney can last as long as possible—potentially for the patient’s entire life.

Kidney prioritization: A kidney donor protection offered through Donor Shield that gives living kidney donors priority access to a compatible kidney transplant through the NKR if they ever need one in the future.

Paired exchange (also paired donation or kidney paired donation, KPD): A type of kidney donation where a donor donates their kidney to another recipient in exchange for a compatible kidney for their friend or family member. The NKR is increasingly transitioning from KPD to the Voucher Program, which does not require the transplants to take place simultaneously and eliminates the need for direct exchanges between incompatible pairs.

Microsite Program: A free service offered by the NKR that provides personalized websites to help patients in need of a kidney transplant find a living donor. Patients can share their story and photos on the microsite, which also includes basic information about living donation and a link to start the evaluation process. Microsite patients receive a custom URL and free business cards and posters.

Microsite: A free, personalized website provided by the NKR to help patients in need of a transplant find a living kidney donor.

Nephrologist: A medical doctor specializing in kidney health, diagnosing and treating conditions like chronic kidney disease, hypertension, electrolyte imbalances, and kidney failure.

Organ Procurement and Transplantation Network (OPTN): The national system that manages the organ transplant process in the United States, including maintaining the transplant waiting list, matching donors with recipients, and establishing policies to ensure fair and effective organ allocation. It is operated under federal contract by UNOS (United Network for Organ Sharing).

Peritoneal dialysis: A type of dialysis that uses the lining of the abdomen (the peritoneum) as a natural filter to remove waste products and excess fluid from the blood. A cleansing fluid (dialysate) is introduced into the abdominal cavity through a catheter. Waste and extra fluids pass from the blood vessels in the peritoneum into this fluid, which is then drained and replaced. It is typically performed at home and can be done manually during the day or automatically overnight using a machine.

Polycystic kidney disease (PKD): A genetic disorder affecting roughly 500,000 people in the United States in which clusters of fluid-filled cysts develop in the kidneys, causing them to enlarge and lose function over time. It is a leading cause of kidney failure. 

Post-transplant microsite: A microsite that is kept live after the transplant has occurred in order to raise awareness about living kidney donation and remain eligible for future voucher opportunities.

Preemptive transplant: A surgical procedure in which a patient with end-stage kidney disease receives a new kidney before starting dialysis. It is considered the optimal treatment for kidney failure, offering better survival rates, higher quality of life, fewer complications, and lower costs compared to having a transplant after dialysis has already begun.

Remote donation: An NKR program that allows donors to undergo testing and surgery at an NKR Member Center close to their home, regardless of where the recipient’s center is located.

Sensitization/sensitized: A condition in which a kidney patient’s immune system has developed antibodies that react to potential donor organs, making it harder to find a compatible kidney for transplant. Doctors use cPRA to assess how sensitized a person is to potential organ donors. Patients with a CPRA over 80% are considered highly sensitized, meaning that their body would likely reject about 80% of donor kidneys.

Standard Voucher Program: A program created by the NKR to enable the best possible donor–recipient matches and to allow kidney donors to donate to the recipient of their choice, even if they are not medically compatible. Standard voucher donors donate according to their schedule, generating a voucher for someone in imminent need of a transplant (the intended recipient or voucher holder). When the voucher holder is ready for a transplant, they can redeem the voucher to receive a transplant from a well-matched living kidney donor. The Standard Voucher Program is offered exclusively by participating NKR Member Centers.

United Network for Organ Sharing (UNOS): A nonprofit organization that manages the U.S. organ transplant system. It maintains the organ transplant waiting list, matches donors with recipients, and oversees policies to ensure fair and efficient allocation of organs.

Waitlist: In the context of organ donation, the list of patients who are registered and waiting to receive a deceased donor organ transplant. The waitlist for kidney transplantation is controlled and managed by the United Network for Organ Sharing (UNOS).