A kidney transplant is the transfer of a healthy kidney from one person (the donor) into the body of a person who has little or no kidney activity (the recipient).
The kidneys are two bean-shaped organs located on each side of the body, just beneath the ribcage. Their main role is to filter waste products from the blood before converting them to urine.
If the kidneys lose this ability then waste products can build up, which is potentially dangerous and can be life threatening.
Loss of kidney function is known as end stage chronic kidney disease or kidney failure, which is the most common reason for a kidney transplant.
It is possible to replicate the functions of the kidney using a blood filtering procedure known as dialysis. But dialysis can be both inconvenient and time-consuming so a kidney transplant, when possible, is the treatment of choice for end stage chronic kidney disease.
Read more about why a kidney transplant is performed.
A person only needs one kidney to survive. Therefore, unlike other types of organ donation, such as heart and liver, a living person can donate a kidney. Ideally, this will be a close relative.
This type of donation is known as a living donation.
Receiving a donation from a close relative means there is less risk of the body rejecting the kidney.
Kidney donations are also possible from donors who have recently died. However, this type of kidney donation has a slightly lower chance of long-term success.
Read more about how a kidney transplant is performed.
One of the biggest risks of receiving a donated kidney is that your immune system (your body's natural defence against infection) will mistake the donated kidney for a foreign object, such as a viral or bacterial infection.
If this happens, your immune system will attempt to destroy the kidney. This is known as rejection.
Potentially, rejection can be very serious and, in some cases, fatal. To minimise risks the kidney should ideally be donated by somebody who has:
- the same tissue type as the recipient. Human tissue carries a special genetic 'marker' or code, known as a human leukocyte antigen (HLA); ideally, you should receive your transplant from someone with an identical, or very similar, HLA tissue type
- the same blood group as the recipient. As with tissue, each red blood cell is marked with a specific antigen marker
For these reasons family members are usually the most suitable donors.
As members of the same family often share the same type of genes they are more likely to have matching HLA tissue types, and blood groups.
However, many kidney transplants have been successfully performed using a donation not taken from a family member.
In some cases there may be two living donors (who are strangers to each other) who do not have the same tissue type as their family member but would be suitable for donation to the other donor's family member and (vice versa.) In such a circumstance they can 'swap' donations. This is known as a paired donation.
A kidney transplant is a major surgical procedure with a wide range of potential risks.
In the short term, rejection, infection and blood clots are a risk. Long term risks are usually related to the medication needed to reduce the chance of rejection (immunosuppressants).
Because of this people who have had a kidney transplant require regular check-ups for the rest of their life.
Read more about the risks of a kidney transplant.
Living with a transplant
Having a healthy lifestyle goes a long way to minimising these types of risks.
It's recommended that you:
Read more living with a transplant.
How common are kidney donations?
The demand for donated kidneys in the UK is far higher than the available supply of donors, both living and dead.
From April 2010 to April 2011 there were 1,020 living donations and 1,667 donations taken from recently deceased people. But this still left just under 7,000 people on the waiting list for a donation.
Kidney donors are particularly required from people of non-white ethnic origin
Chronic kidney disease is especially high in communities of South Asian and African or Carribbean ethnic origin, but there are not many donors from these communities.
Read more about black health and South Asian health issues.
The outlook for a person who receives a donated kidney will depend on a number of factors. These include:
- whether the donation was a living donation or not (living donations usually have a slightly better outlook)
- whether the donation was from a close relative or someone with the same tissue type (this lowers the risk of the body rejecting the kidney)
- the age of the person receiving the donation (the younger the person, the better the outlook)
- the overall health of the person receiving the donation (the healthier a person is, the better the outlook)
The kidney survival times for living donations are:
- 1 year - 90-95%
- 5 years - 80%
- 15 years - 60%
Where kidneys are donated from someone who has recently died, the kidney survival times are:
- 1 year - 85-90%
- 5 years - 70%
- 15 years - 50%