Kidney transplantation

 

Kidney transplantation is the most common type of whole organ transplant.

The main indication for kidney transplantation

End-stage renal disease

Absolute contraindications include:

 

Comorbidities that can adversely affect graft survival (eg, severe heart disease, malignancy) are detected by a comprehensive examination

 

Relative contraindications include the following:

 

●     Poorly controlled diabetes, which can lead to rapid transplant rejection

●     Patients in their 70s and sometimes 80s may be transplant candidates if they are generally healthy, functionally independent, with good social support, with a relatively favorable life expectancy, and if transplantation is expected to significantly improve quality of life by getting rid of dialysis. Patients with type I diabetes may also be candidates for transplantation, provided that both pancreas and kidney or pancreas after kidney are transplanted at the same time. Riverside Nephrology Physicians provide the best kidney Transplant Coordinator in USA.

kidney donors

More than half of donor's kidneys come from healthy people who are in a state of brain death. About one-third of these kidneys are marginal with physiological or transplant procedure impairments, but they are used because the need is so great.

 

The most commonly used kidneys are from asystolic donors (grafts obtained from so-called donation after the death of the heart [DPSS]). These kidneys can be damaged by ischemia before the death of the donor, and their function is often compromised due to acute tubular necrosis; however, over the long term, they function just as well as kidneys from donors who meet standard criteria (called Standard Donor Criteria [SKD]).

 

The remaining donor kidneys (another 40%) are taken from living donors; Since the number of organs is limited, allografts from carefully selected living unrelated donors are increasingly being used. Living donors may have impaired renal function, which is associated with risks associated with the organ donation procedure, may have long-term health problems, and may experience psychological problems associated with organ donation; therefore, donors are screened for confirmation of normal function of both kidneys, the absence of systemic diseases, tissue compatibility, emotional stability and capacity for informed consent regarding organ retrieval. High blood pressure, diabetes mellitus, sociopathology (with the exception of tumors of the central nervous system) in the perspective of living donors, as a rule,

 

The use of non-living donor kidneys is increasing; kidney exchange programs often bring together a potential donor and recipient who are incompatible with other similar incompatible couples. When multiple such pairs are identified, chain exchanges are possible, greatly increasing the potential for a high degree of match between recipient and donor.

 

If an ABO match is not possible, an ABO-incompatible transplant can sometimes be done; with careful selection of donors and recipients, and with graft pretreatment (plasma exchange and/or intravenous immunoglobulins [IGIV]), results may be comparable to ABO-compatible graft transplantation.

 

kidney transplant procedure

The donor's kidney is removed by laparoscopic (or, rarely, open) surgery, perfused with chilled solutions containing relatively high concentrations of poorly penetrating substances (eg, mannitol, hydroxyethyl starch) and electrolyte concentrations close to intracellular levels; the kidney is then stored in a frozen solution. With this method of preparation, kidney function is well preserved, provided that transplantation occurs within 24 hours. Although not commonly used, it is possible to increase ex vivo viability up to 48 hours with continuous pulsatile hypothermic perfusion with an oxygenated, perfused plasma solution.

 

The recipient may require dialysis prior to transplantation to maintain a relatively normal metabolic state, but living-donor allografts survive slightly better in recipients who did not receive long-term dialysis prior to transplantation.

 

Nephrectomy of the recipient is usually not required if there is no infection in the own kidneys.

 

It is not known whether a blood transfusion is beneficial for patients with anemia and waiting for an allograft; transfusion may sensitize patients to alloantigens, but the allograft survives better in transfused recipients who are not sensitized; this may be due to the fact that transfusion induces some form of tolerance.

 

The transplanted kidney is usually placed in the iliac fossa. Anastomoses of the kidney vessels with the iliac vessels are formed, the donor ureter is implanted into the bladder, or an anastomosis is formed with the recipient's ureter. Vesicoureteral reflux occurs in 30% of recipients but usually has no adverse reactions.

 

Immunosuppressant regimens vary (see table Immunosuppressants Used to Treat Transplant Rejection ). An induction agent (eg, antithymocyte globulin, alemtuzumab) is administered intraoperatively in nearly all kidney transplant recipients. Ciclosporin is usually given intravenously during or immediately after transplantation and then orally thereafter at doses that minimize toxicity and risk of rejection and maintain blood levels high enough to prevent rejection. On the day of transplantation, glucocorticoids are also started intravenously or orally; the dose is reduced to a minimum over the following weeks, depending on the protocol used.

 

Complications in kidney transplantation

 

rejection

Despite the use of immunosuppressants, 20% of kidney transplant recipients have one or more episodes of rejection. Most cases are easily treated with corticosteroid boluses; however, they contribute to the development of long-term failure and/or damage to the graft. Signs of rejection vary by type (see table Manifestations of Kidney Transplant by Rejection Category ).

 

If the diagnosis is clinically unclear, then rejection can be diagnosed by needle biopsy through the skin. A biopsy helps differentiate antibody-mediated from T-lymphocyte-mediated rejection, as well as other causes of transplant complications (eg, calcineurin inhibitor toxicity, diabetic or hypertensive nephropathy, type I polyomavirus infection). More precise tests to clarify the diagnosis of rejection include measuring the urinary levels of mRNAs encoding rejection mediators and the gene expression profile of biopsy specimens using DNA microanalysis.

 

Intensive immunosuppressive therapy (eg, with high-dose glucocorticoid pulse therapy or antilymphocyte globulin) usually stops accelerated or acute rejection. If immunosuppressants are ineffective, their dose is reduced and hemodialysis is resumed until another graft is available.

 

Transplant nephrectomy is necessary if there is hematuria, tenderness at the graft site, or fever after stopping immunosuppressants.

 

Chronic allograft nephropathy

Chronic allotransplantation nephropathy results in graft failure or damage 3 months after transplantation. Most cases are due to causes such as intoxication with calcineurin inhibitors, diabetic or hypertensive nephropathy, or infection with type I polyomavirus. Some experts suggest that the term should be used to describe graft failure or damage when the biopsy establishes that chronic interstitial fibrosis and tubular atrophy are not due to any other cause.

 

Cancer

Compared with the general population, kidney transplant recipients are, on average, 10 to 15 times more likely to develop cancer, probably because the response of the modulated immune system to cancer cells as well as infectious diseases is attenuated. Cancer of the lymphatic system (lymphoma) is 30 times more common among kidney transplant recipients than in the general population, but lymphoma is still a rare disease. Skin cancer is becoming common among kidney transplant patients after years of immunosuppression.

The prognosis for kidney transplant

The greatest number of cases of rejection and other complications occurs within 3-4 months after transplantation; most patients recover their normal health and activity, but they must continue to take maintenance doses of immunosuppressants.

 

Within 1 year after kidney transplantation, survival is:

 

●     Transplants from living donors: 98% (patients) and 94% (grafts)

●     Transplants from dead donors: 95% (patients) and 88% (grafts)

●     In the future, the annual death of the graft is 3–5% for kidney transplantation from living donors and 5–8% for kidney transplantation from cadaveric donors.

 

Of patients with graft survival greater than one year, half die from other causes (eg, cardiovascular disease, infections) with a normally functioning graft; half develop chronic allograft nephropathy against the background of graft dysfunction within 1–5 years. The incidence of late graft loss is higher in blacks than in whites.

 

Doppler ultrasound measurement of peak systolic and minimum end-diastolic current in renal segmental arteries 3 months or more after transplantation may help assess prognosis.

 

remains the best clinical predictor

 

Sequential determination of serum creatinine

In a given patient, most recently obtained creatinine levels should be comparable to previous levels; a sudden increase in creatinine indicates the need to consider rejection or another problem (eg, vascular injury, ureteral obstruction). Ideally, serum creatinine levels should be normal in all transplant patients.