Kidney transplantation

Kidney transplantation (renal transplantation) is the surgical placement of a healthy donor kidney into a person with kidney failure.[1] It is the most commonly performed solid-organ transplant and is the preferred treatment for many people with end-stage renal disease (ESRD), offering better survival and quality of life than long-term dialysis for suitable candidates.[1][2] The donor kidney is usually placed heterotopically in the lower abdomen (the iliac fossa) rather than in the native kidney's location, and the native kidneys are typically left in place.[1] Kidneys may come from deceased or living donors.

Indications

The principal indication is end-stage renal disease, irreversible kidney failure (commonly defined around an estimated glomerular filtration rate below 20 mL/min/1.73 m²), most often due to diabetes mellitus, hypertension, glomerulonephritis, or polycystic kidney disease.[1][2] Preemptive transplantation, performed before dialysis is required, is associated with the best outcomes.[1] Candidacy is assessed at a transplant center, weighing the benefits of transplantation against surgical and immunosuppression risks.

Contraindications

Absolute and relative contraindications include active untreated malignancy, active uncontrolled infection, severe irreversible comorbidity that would not be improved by transplantation, and inability to adhere to immunosuppression; these are evaluated individually rather than applied as rigid rules.[1][2]

Donor source

• Living-donor kidneys generally have superior graft survival and shorter (or zero) waiting times; living donation may be directed, non-directed, or arranged through kidney paired donation. See Living donation.[3]
• Deceased-donor kidneys supply most transplants; donor quality is summarized by the Kidney Donor Profile Index (KDPI).[4]

Procedure

The donor kidney is implanted in the iliac fossa through an extraperitoneal approach.[1] The renal artery and vein are anastomosed to the recipient's external iliac (or other pelvic) vessels, and the donor ureter is connected to the recipient's bladder (ureteroneocystostomy), often over a temporary stent.[1] Blood flow is restored (reperfusion), and the kidney typically begins producing urine intraoperatively or shortly thereafter; delayed graft function, often requiring temporary dialysis, can occur, particularly with higher-KDPI or DCD organs.[1]

Allocation

Deceased-donor kidneys are allocated through the OPTN match run under the Kidney Allocation System.[5] Key factors include waiting time (counted from the start of dialysis or qualifying low GFR), candidate sensitization measured by calculated panel-reactive antibody (cPRA) (with priority for highly sensitized candidates), the Estimated Post-Transplant Survival (EPTS) score, ABO blood type, and HLA considerations, with the KDPI describing donor quality.[5] Geographic distribution uses acuity circles defined by nautical-mile distance from the donor hospital. Highly sensitized candidates and prior living donors receive allocation priority. Allocation mechanics are detailed in dedicated allocation-policy articles.

Immunosuppression

Recipients receive induction immunosuppression at transplantation (commonly an anti-thymocyte globulin or an interleukin-2 receptor antagonist) followed by lifelong maintenance therapy, most often a combination of a calcineurin inhibitor (tacrolimus), an antiproliferative agent (mycophenolate), and a corticosteroid.[6] See Transplant immunology.

Rejection and complications

Rejection may be hyperacute, acute (T-cell-mediated or antibody-mediated), or chronic; it is diagnosed by graft dysfunction and biopsy graded with the Banff classification, supplemented by donor-derived cell-free DNA in some programs.[7] Other complications include surgical and vascular problems (renal artery or vein thrombosis, lymphocele, urine leak), opportunistic infections (notably cytomegalovirus and BK polyomavirus nephropathy), malignancy including post-transplant lymphoproliferative disorder, calcineurin-inhibitor nephrotoxicity, new-onset diabetes after transplantation, and recurrence of the original kidney disease.[1][6]

Outcomes

Kidney transplantation improves survival and quality of life relative to dialysis for suitable candidates, and living-donor grafts generally outlast deceased-donor grafts.[1][2] Program- and national-level outcome statistics are published by the Scientific Registry of Transplant Recipients (SRTR) and OPTN and should be consulted for current, dated figures.

History

The first successful human kidney transplant was performed in 1954 in Boston by Joseph Murray and colleagues, between identical twins, avoiding rejection; Murray shared the 1990 Nobel Prize in Physiology or Medicine for this work.[8] The introduction of effective immunosuppression, culminating in ciclosporin in the early 1980s, made transplantation between unrelated, non-identical individuals routinely successful.[8]

See also

• Organ transplantation · Living donation · Deceased donation
• Transplant immunology

References

• Kidney Transplantation. StatPearls. NBK567755. https://www.ncbi.nlm.nih.gov/books/NBK567755/
• National Kidney Foundation / MedlinePlus. Kidney transplant. https://medlineplus.gov/ency/article/003005.htm
• HRSA/OPTN. Living donation. https://www.hrsa.gov/optn/professionals/resources/ethical-considerations/living-non-directed-organ-donation
• HRSA/OPTN. A Guide to Calculating and Interpreting the KDPI. https://www.hrsa.gov/sites/default/files/hrsa/optn/kdpi_guide.pdf
• United Network for Organ Sharing. How we match organs (kidney allocation; KDPI, EPTS, cPRA, acuity circles). https://unos.org/transplant/how-we-match-organs/
• Immunosuppression in transplantation. StatPearls. NBK558995. https://www.ncbi.nlm.nih.gov/books/NBK558995/
• Transplant Rejection (Banff classification). StatPearls. NBK553074. https://www.ncbi.nlm.nih.gov/books/NBK553074/
• The Nobel Prize in Physiology or Medicine 1990 (Joseph E. Murray). https://www.nobelprize.org/prizes/medicine/1990/summary/