A kidney transplant is the transfer of a healthy kidney from one person into the body of a person who has little or no kidney function.

The main role of the kidneys is to filter waste products from the blood and convert them to urine. If the kidneys lose this ability, waste products can build up, which is potentially life-threatening.

This loss of kidney function, known as end-stage chronic kidney disease or kidney failure, is the most common reason for needing a kidney transplant.

It's possible to partially replicate the functions of the kidney using a blood filtering procedure known as dialysis. However, this can be inconvenient and time-consuming, so a kidney transplant is the treatment of choice for kidney failure whenever possible.

Who can have a kidney transplant?

Most people who need a kidney transplant are able to have one, regardless of their age, as long as:

• they're well enough to withstand the effects of surgery
• the transplant has a relatively good chance of success
• the person is willing to comply with the recommended treatments required after the transplant – such as taking immunosuppressant medication and attending regular follow-up appointments

Reasons why it may not be safe or effective to perform a transplant include having an ongoing infection (this will need to be treated first), severe heart disease, cancer that has spread to several places in your body, or AIDS.

Around one in three people with kidney failure is suitable for a transplant.

Kidney donations

Unlike many other types of organ donation, it's possible to donate a kidney while you're alive because you only need one kidney to survive. This is known as a living donation.

People who want to be considered as a kidney donor are tested very carefully to ensure they are a suitable donor and are fit for the operation needed to remove a kidney.

Ideally, living donations will come from a close relative because they are more likely to share the same tissue type and blood group as the recipient, which reduces the risk of the body rejecting the kidney.

Kidney donations are also possible from people who have recently died. This is known as deceased kidney donation. However, this type of kidney donation has a slightly lower chance of long-term success.

Waiting for a kidney

People who need a kidney transplant, but don't have a suitable living donor, will have to wait until a suitable deceased donor kidney becomes available.

On average, the waiting time for a deceased donor kidney transplant is two to three years. Waiting times are so long because the demand for donated kidneys in the UK is far higher than the available supply of donors.

From April 2014 to April 2015, around 3,000 kidney transplants were carried out in the UK, but there were still more than 5,000 people on the waiting list for a kidney by the end of this period.

Kidney donors are particularly required from people of non-white ethnic origin, because rates of kidney disease are especially high in people of South Asian, African and Caribbean ethnic origin. However, there are not many donors from these communities.

The transplant procedure

If you receive a kidney from a living donor, this will be a carefully planned operation.

If you're waiting for a deceased donor kidney, the transplant centre will contact you when a suitable kidney becomes available. This can happen at any time of the day or night. Staff at the centre will check you don't have any new medical problems and will ask you to go to the centre, where final checks will be performed to be sure the transplant should go ahead.

You'll then have surgery to insert the new kidney and connect it to your blood vessels and bladder. The new kidney will be placed in the lower part of your abdomen (tummy). Your own kidneys will usually be left in place.

A kidney transplant is a major surgical procedure with a wide range of potential risks. In the short term, these risks include blood clots and infection. Longer-term problems, which include diabetes and an increased risk of infections, are usually related to the medication you need to take to reduce the chance of rejection.

Because of the risk of further problems, people who have had a kidney transplant require regular check-ups for the rest of their life.

Living with a kidney transplant

Having a healthy lifestyle after a kidney transplant goes a long way to minimise the risk of complications.

Therefore, it’s recommended that you:

• stop smoking if you smoke
• eat a healthy diet
• lose weight if you are overweight or obese
• take steps to reduce your risk of developing infections

How long do kidney transplants last?

There are a number of factors which affect how long a transplanted kidney lasts.

These include whether or not the kidney came from a living donor, how well the kidney is matched in terms of blood group and tissue type, and the age and overall health of the person receiving the donation.

Overall, average kidney survival times are:

• 1 year – about 95%
• 5 years – about 85-90%
• 10 years – about 75%

If you have a kidney transplant that fails, you can usually be put on the waiting list for another transplant. You may need dialysis in the meantime.