Kidney or Renal Transplantation

Kidneys have the important function of removing toxins from the body by filtering the blood. Due to different reasons, this function can get disrupted and lead to chronic kidney disease. As described in a previous blog post, depending on the stage, the patient is treated through lifestyle modifications and dialysis, and might finally end up needing a new kidney. Dialysis is the procedure of removing toxins and excess fluid from the body which often involves passing the blood through an external machine. Kidney transplantation, on the other hand, involves placing a healthy kidney from a deceased or living person in a patient whose kidneys do not function anymore. Kidney transplantation is mostly the recommended treatment procedure for patients in the last stage of chronic kidney disease called end-stage renal disease.

Before doing a kidney transplant, the patient and the donor are examined for many criteria like their age and health status, and are thoroughly examined for their physical condition through routine laboratory tests and specialized tests. Most importantly, the blood compatibility between patient and donor has to be matched to proceed with the transplantation. With all these checks in place, kidney transplants have been quite successful. The Scientific Registry of Transplant Recipients (SRTR) reported the 1-year national (USA) survival rate as 98.11% success rate for a living donor transplant and 94.88% for a deceased donor transplant.

Delayed Function of Transplanted Kidney

Despite the general overall statistics of successful kidney transplants, there is a chance of temporary kidney function failure immediately post the transplant. This acute kidney failure condition is termed “delayed graft function”. It is defined specifically as the requirement of dialysis within 7 days of transplantation. The rate of having a delayed graft function is about 25–35% when the kidney is donated from a deceased patient. With a living donor transplant, this rate is lower but can still occur.

While, as indicated by the term, the kidneys start functioning after the delay, there are other consequences due to the delay. In delayed graft function transplants, long-term outcomes are worse, and there is an increased incidence of poor graft function and in some cases complete rejection of the graft within one year of transplant.

Moreover, there is no known treatment for delayed graft function or the longer-term consequences. Therefore, the onus lies in understanding the factors that can cause it and trying the best to avoid them.

Current Understanding of Delayed Graft Function

The major problem with this health issue is that the exact biological reason for a delayed graft function is not completely understood yet. However, one of the most probable causes could be the injury caused when kidneys that have been devoid of oxygen (ischemia) during the transplantation procedure are suddenly flooded by oxygen (reperfusion) after the transplantation is complete. This injury is accompanied by the release and activity of inflammatory molecules which can be hindering to achieve proper kidney function.

Associated Factors of Delayed Graft Function

While treatments for the condition are being researched, it can potentially be avoided by understanding associated factors that might cause delayed graft function. In a recently published open-access research article, the authors conduct a comprehensive analysis of factors associated with delay in graft function. They revisited the medical history of 531 transplant patients collected over 11 years.

Firstly, it was seen that the age of the patient and donor affected the graft function. The older they were, the higher were the chances of delay in function. The main reason could be general medical conditions including comorbidities.

Secondly, the cold ischemia time, defined as the time between when the kidney graft is outside in cold preservation solution and finally grafted and connected to the recipient’s blood supply, significantly affects the outcome of the transplant. In this report, the authors found that when the cold ischemia time was over 15 hours, the delay in graft function increased substantially. This is also one of the reasons why the chance of delayed graft function was higher when the transplant was from a deceased donor compared to that from a living donor.

The matching of donor-recipient blood types was another important factor. Human leukocyte antigens (HLA) are proteins on the cell surface of human cells which help in regulating the immune system. These are the proteins that are matched between donors and recipients, and a significant mismatch can lead to poor outcomes. Usually, immunosuppressants are administered to combat this problem after transplantation. In the study mentioned, the researchers further found that a specific type of antigen mismatch (HLA-DR) specifically correlated with the delayed graft function. Therefore, administering immunosuppressants for this specific factor is also important.

One finding of the study was also that when patients had delayed graft function, the long-term renal function was poorer than those transplants that immediately functioned.

Take-Home Message for Patients

All the factors discussed above regarding chances of a delayed graft function have been consistent with other studies. Therefore, there is a need to be aware of these predictors. As research continues to find solutions to reduce the chances of delayed graft function, here are some factors that the patient can discuss and work on with the medical system: ensure reduced ischemia time (time the kidney is outside of the body without blood supply) and carefully choose the immunosuppressants by anticipating the chance of delayed graft function based on age, comorbidities and blood compatibility between donor and recipient.