Kidney transplantation

A kidney transplant, or renal transplant, is a surgical procedure used to treat end-stage kidney disease (ESRD). ESRD occurs when the kidneys can no longer perform their vital functions, such as filtering waste from the blood. This condition is defined by a glomerular filtration rate of less than 15 ml/min/1.73 m2.

Replacing a failing kidney with a healthy one can offer a patient a better quality of life. Most patients with ESRD live longer after a transplant than those who rely on dialysis. Dialysis is a process used to clean the blood when the kidneys fail, but a transplant is often a more effective long-term solution.

The mechanism of a transplant involves placing a new kidney into the recipient's body. During the surgery, the new organ is usually positioned in the lower abdomen. Interestingly, surgeons do not typically remove the patient's original, diseased kidneys. They only remove the native kidneys if a specific medical reason requires it.

Once implanted, the new kidney must begin filtering blood immediately to support the patient's health.

There are different types of donors that provide these organs. Transplants are classified as either deceased-donor or living-donor transplants. Deceased-donor transplants come from individuals who have died. Living-donor transplants come from people who are still alive. Living donors can be genetically related to the recipient or non-related.

In the United States, the use of living donors is currently rising.

History shows that scientists have long dreamed of organ substitution. In 1907, researcher Simon Flexner suggested that replacing diseased organs with healthy ones might one day be possible. In 1933, surgeon Yuriy Vorony attempted a human kidney transplant in Ukraine. This attempt failed because the kidney was incompatible with the recipient's blood group. The first truly successful kidney transplant occurred on December 23, 1954, at Brigham Hospital in Boston.

A team led by Joseph Murray performed the surgery on identical twins, Ronald and Richard Herrick. Because they were identical twins, the body was less likely to react against the new organ. Joseph Murray later received a Nobel Prize in 1990 for this groundbreaking work.

The most significant challenge in transplantation is the recipient's immune system. The immune system often views a transplanted kidney as "non-self" and attempts to attack it. This process is known as rejection. Rejection can be classified as cellular rejection or antibody-mediated rejection.

Antibody-mediated rejection can be hyperacute, acute, or chronic, depending on how long after the surgery it occurs. To prevent this, patients must take immunosuppressants, which are medications that suppress the immune system. While these drugs protect the kidney, they also increase the risk of infections and cancer, such as lymphoma.

Doctors use several medications to manage the immune response. Prednisolone is a common corticosteroid used in these regimens. However, long-term use of high-dose prednisolone can cause side effects like diabetes, weight gain, and osteoporosis. To reduce these risks, doctors often use non-steroid agents such as azathioprine, mycophenolate, ciclosporin, or tacrolimus. These allow for lower doses of prednisolone to be used.

To ensure the kidney stays healthy, doctors monitor the patient at least every three months. They measure serum creatinine and may use donor-derived cell-free DNA (dd-cfDNA) blood testing to detect early signs of rejection.

Transplantation is a massive global medical effort. In 2018, an estimated 95,479 kidney transplants were performed worldwide. Of these, 36% came from living donors. In the United States, patients waiting for a deceased donor kidney face an average wait time of three to five years. Many people face various causes for kidney failure, with diabetes being the most common known cause, accounting for about 25% of transplants in the U.S. Because kidney transplantation was relatively simple compared to other organs, it served as the foundation for moving toward heart and liver transplants.