What is a kidney transplant?
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:
- quit smoking if you smoke
- eat a healthy diet
- lose weight if you are overweight or obese; ideally you want to achieve a body mass index of less than 25.
- Read more living with a transplant.
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.
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%
Risks of a kidney transplant
Due to the introduction of newer, more effective immunosuppressant medications during the 1980s, rates of serious complications that arise after a kidney transplant have fallen sharply.
However, kidney transplants, like any other type of surgery, are not risk free. The risks of a kidney transplant can arise from a number of factors:
- risks related to the procedure itself
- risks related to the use of immunosuppressant medications
- risks related to something going wrong with the transplanted kidney
In turn, complications can occur in the first few months after a transplant or, alternatively, not for many years, and in some cases, decades.
Both short-term and long-term complications of a kidney transplant are discussed below.
After a transplant, minor infections are common. They affect an estimated one in two people. These infections usually take the form of:
More serious infections, such as pneumonia (a lung infection) and cytomegalovirus (a viral infection that can be severe in people with weakened immune systems) can occur and may require aggressive treatment and admission to hospital.
Blood clots can develop in the arteries that have been connected to the donated kidney. They are estimated to develop in around one in 30 kidney transplant cases.
In some cases, it may be possible to dissolve the blood clots using medication. In more serious cases, where clotting does not respond to treatment, it is usually necessary to remove the donated kidney.
Narrowing of an artery
In an estimated one in 20 cases, the arteries connected to the donated kidney become narrowed. This is known as arterial stenosis.
Arterial stenosis can develop months or even years after the transplant. It can cause a sudden rise in blood pressure, which is potentially dangerous. Surgery is usually required to widen the artery, often using a small metal tube called a stent.
Ureteral obstruction and urinary leakage
Ureteral obstruction is a common complication after a kidney transplant. It develops when the ureter (the tube that carries urine from the kidney to the bladder) becomes blocked from clots of tissue or fluid that form during or after the operation.
The symptoms of a ureteral obstruction include:
- a high temperature (fever) of 38C (100.4F) or above if infection is also present
- pain in the side of your abdomen (stomach)
- feeling sick
- being sick
- blood in your urine
It may be possible to unblock the ureter by draining it with a small tube called a catheter. The catheter is inserted into your urethra (the opening in the penis or vagina that urine flows out of), before being guided into your ureter. If this treatment does not work, surgery may be required to unblock the ureter.
Urine may leak from any part of the urinary system (the kidney, bladder, ureter and urethra) as a result of damage or disruption caused during surgery. Urine leakage usually occurs during the first month after surgery.
Symptoms of urine leakage include:
- fluid leaking from the site of your surgical incision
- abdominal (stomach) pain
- swelling of your perineum (the area of skin between your genitals and anus)
Small leaks can be treated using a catheter to drain away the excess urine.
However, larger leaks may require surgery to correct them. Ureteral obstruction and urinary leakage occur in an estimated 3-5% of kidney transplant cases.
Acute rejection is where the immune system suddenly begins to attack the donated kidney because it mistakes it for a foreign object.
Despite the use of immunosuppressants, acute rejection is a common complication in the first year after a transplant, affecting an estimated one in five people.
In many cases, acute rejection does not cause noticeable symptoms, and is only detected during a blood test.
Acute rejection can usually be successfully treated using a short course of more powerful immunosuppressants.
Side effects of immunosuppressants
Immunosuppressants prevent your body's immune system from attacking the new kidney, which would cause the transplanted kidney to be rejected.
Widely used immunosuppressants are:
The downside of taking immunosuppressants are that they can cause a wide range of side effects, including:
- loss of appetite
- feeling sick
- being sick
- stomach pain
- swollen gums
- bruising or bleeding more easily
- extra hair growth
- weight gain
The doctor in charge of your care will be trying to find the right dose that is high enough to 'dampen' the immune system sufficiently to stop rejection, but low enough that you experience very few, or no, side effects.
Finding the optimal dose to achieve both goals is often a difficult balancing act. It may take several months to find the most effective dose that causes the least amount of side effects.
Side effects should improve once the right dosage is identified. Even if your side effects become troublesome, never suddenly stop taking your medication because your kidney could be rejected.
Contact the doctor in charge of your care for advice.
Diabetes is a common complication of having a kidney transplant. Diabetes is a long-term condition that causes high blood glucose levels and can be triggered by a number of (not always negative) factors, such as:
- people tend to eat more and put on weight after a transplant as they no longer feel ill all the time
- some types of immunosuppressants can make you more likely to develop diabetes
Symptoms of diabetes include:
- feeling very thirsty
- going to the toilet a lot, especially at night
- extreme tiredness
Diabetes can often be controlled using a combination of lifestyle changes – such as getting more exercise – and medication. Read more about the treatment of diabetes.
High blood pressure
High blood pressure is another common complication of a kidney transplant.
Many people who require a kidney transplant already have an increased risk of developing high blood pressure and taking immunosuppressants can make the condition worse.
High blood pressure usually causes no noticeable symptoms but can increase your risk of developing other serious, and in some cases fatal, health conditions, such as:
- coronary heart disease
- heart failure
- heart attack
Because of the risk of high blood pressure you should be given a blood pressure test every time you attend one of your follow-up appointments. In addition to this you can check your own blood pressure at home with a simple device available from most chemists.
Read more about treating high blood pressure.
The long-term use of immunosuppressants does increase your risk of developing some types of cancer.
Often these are types of cancer known to be caused by viruses (as you will be more vulnerable to the effects of infection.)
- most types of skin cancer
- Kaposi’s sarcoma – a type of cancer that can affect both skin and internal organs
- lymphoma – a cancer of the lymphatic system
- kidney cancer
- cervical cancer
If you are taking immunosuppressants, you also have a much higher risk of developing skin and lip cancers.
Avoid going out in the sun during the hottest part of the day and apply complete sun block to your lips and all exposed areas of your skin every day, regardless of whether or not it is sunny.
Your care team will be able to provide more advice on your individual risks, whether you require regular check-ups and any early signs to watch out for.
How is a kidney transplant performed?
When a suitable donor kidney is found, the transplant centre will contact you. It will check no new medical problems have occurred and will ask you to go to the centre.
When you hear from the transplant centre:
- do not eat or drink anything
- take all current medicines with you
- take a bag of clothes and essential items for your hospital stay
When you arrive at the transplant centre, you will be quickly reassessed. Some of the tests you had at your initial assessment may be repeated to ensure no new medical conditions have developed.
At the same time, a second medical team will examine the donor kidney if the kidney was taken from a recently deceased donor. (If the donation is being provided by a living donor then these tests are carried out well in advance of the surgery.)
The procedure must be carried out as quickly as possible for the transplant to have the best chance of success. After the medical team has confirmed the kidney is in good condition and is suitable, you will be given the general anaesthetic.
A number of different methods can be used to carry out a kidney transplant. The most widely used method is known as a Gibson incision.
A Gibson incision involves a three-stage procedure:
- First, an incision (cut) is made in your lower abdomen (stomach), through which the donated kidney is put into place. Your own kidneys can usually be left where they are, unless they are causing a problem, such as an infection.
- Second, blood vessels from your lower abdomen are attached to the blood vessels of the donated kidney. This is to provide the donated kidney with the blood supply that it needs to function properly.
- Finally, the ureter (the tube that carries urine from the kidney to the bladder) of the donated kidney is connected to your bladder.
While the above procedure may sound relatively straightforward, it is demanding and complex surgery that usually takes three to four hours to complete.
Once you have recovered from the effects of the anaesthetic, it is likely you will feel some pain at the site of the incision. If you are in pain, painkillers will be provided.
After the operation, you will immediately begin treatment with medication designed to prevent your immune system from rejecting your new kidney.
These types of medication are known as immunosuppressants. See living with a kidney donation for more information about immunosuppressants.
In around seven out of 10 people who have a kidney transplant, their new kidney begins working immediately after surgery. However, transplanted kidneys sometimes take up to six weeks to start working. If this is the case, you will need to use dialysis during this time.
Dialysis involves using a mechanical device to replicate the functions of the kidney.
Most people are fit enough to leave hospital after having kidney surgery, but you will need to attend frequent appointments at the transplant centre so your kidney function can be assessed.
Tests are also used to check how well your immunosuppressants are working.
For the first few weeks after surgery, you may need to have two to three appointments a week. However, over time, your appointments will become less frequent. After a year, as long as you do not have any serious problems, you should only have to attend the centre once every two to three months.
After kidney surgery, you should be able to return to work and normal activities within a few months, provided you make good progress.
Former diabetic Ivy Ashworth-Crees talks about how much better her life is since her double kidney and pancreas transplant.
About 32 years ago, I started to have diabetes and had to have insulin injections four times a day. I also had to work hard on my diet to make sure I didn’t eat too much sweet food.
After about 25 years, I got kidney failure and, in 2003, I had to go on kidney dialysis. The kidney dialysis was very uncomfortable. It was a drain, having to do it four times a day, as well as having to have the diabetes injections four times a day. I felt like my life was on hold.
I was on kidney dialysis for two years when they put me on the list to have a kidney transplant. The surgeon suggested that I could probably benefit from a kidney and a pancreas transplant, which meant I wouldn’t be a diabetic any more.
When I got the phone call to say that I was going to Manchester for the transplant, I was absolutely hysterical. I was a bag of emotions, both thrilled and terrified.
When I came round after the operation, I was in intensive care. I stayed there for about three or four days, then I was taken to the main ward.
The most difficult part was getting out of bed and starting to walk. They walked me up and down the ward for weeks until my legs got strong enough. That was very, very difficult. The pain was very bad, but it’s all been worth it.
The doctor asked me to try to reduce my weight, so I joined the gym. I enjoy swimming. I think it’s helping me to keep active. The only problem is that I can’t walk too far.
It’s vital that I take the immunosuppressant drugs. If I don’t, my body could reject the kidney and pancreas. I have to take them for the rest of my life.
My life’s changed dramatically. I now take it for granted that I can eat what I want, including chocolates! I’m back at work, I don’t have an injection after my meals, I don’t have to rush home for dialysis and my kidneys and pancreas are working well.
I feel blessed that I’ve been through this operation and it’s worked so well.
When Dr Carole Angel donated a kidney to her brother, Paul Whitaker, she was able to go home just 48 hours after surgery.
Paul, a 39-year-old self-employed builder from Preston, was diagnosed with end-stage kidney failure in October 2001. "I was astonished to find out I had renal failure," he says. "After a series of headaches, I went to the optician because I thought I needed glasses. He tested my blood pressure and it was so high he sent me straight to my doctor."
He began dialysis in the summer of 2002, but his condition rapidly deteriorated and he was soon registered for a transplant.
His older sister Carole was working as a pathologist in Sheffield. She says: "Paul has always been a strong, tall man, but his illness began to take its toll. He lost three stone in weight."
Paul's family were worried about him. "It was worse for Mum, Dad and our brothers, as they all lived closer to him and could see the daily effect on him," says Carole. "I knew one of us should donate a kidney, and it just happened to be me.
"I don't see Paul very often but we have always kept in touch by telephone. When I told him I was willing to donate a kidney, he said that he couldn't ask me to go through with it. I told him he wasn't asking; I was offering. We can be quite stubborn in our family.
"The decision to donate wasn't taken lightly. I had to go through a series of hospital tests and received a lot of psychological support. The whole process took many months. I felt a special responsibility to make sure that my health was good enough to help Paul. The worst thing was not knowing whether it would all go ahead."
Around Christmas 2002, the possibility of 'keyhole' surgery was mentioned by the doctors. It was a relatively new procedure for the Manchester renal transplant unit but offered the great advantage of being much better for the donor, with a shorter hospital stay and quicker recovery time.
However, not all living kidney donors are able to have this technique. It wasn't until Carole woke up after the operation in March 2003 that she knew it had been successful.
"I had the operation on a Thursday morning and was home by lunchtime on Saturday, just 48 hours later. It was incredible. When I was 21, I had my appendix out and that was far worse than the kidney donation operation."
Paul recalls waiting to go into surgery a few hours after his sister. "I must admit, I was worried about what she might be going through. But we managed to see each other as I was being wheeled into theatre and she was being wheeled out. She was very groggy and doesn't remember much, but it gave me a great boost to see her.
"When I eventually came out of surgery, I was wheeled past the side ward where Carole was recovering and she saw me, which made her feel better."
Both Carole and Paul have fully recovered. "The whole experience has changed my outlook on life," says Carole. "Paul is always so positive about things. He always looks on the bright side and this has rubbed off on me."
Paul is back at work again, living life to the full. "I'm overwhelmingly grateful to Carole for what she did for me. She gave me back my life, and I can never thank her enough."
The lifestyle advice below is recommended if you have had a kidney transplant.
If you smoke, it is strongly recommended you quit as soon as possible.
A recent study found people who continued to smoke after a kidney transplant are twice as likely to have that kidney fail than non-smokers.
Your doctor will also be able to recommend and prescribe medication that can help you give up. See Treatment for quitting smoking for more information.
A healthy diet should consist of :
- plenty of fruit and vegetables – at least five portions of fruit and veg a day
- plenty of potatoes, bread, rice, pasta and other starchy foods; ideally you should choose wholegrain varieties
- some milk and dairy foods
- some meat, fish, eggs, beans and other non-dairy sources of protein
- a small amount of food and drink high in fat and sugar
Also avoid food that contains high levels of salt, as salt can raise your blood pressure, which can be dangerous in people with a kidney transplant.
Exercise and weight loss
Once you have made a sufficient physical recovery from effects of surgery it is recommended that you do regular physical activity.
Adults should do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity every week.
The definition of moderate intensity physical activity is any activity that increases your heart and breathing rate and may make you sweat but you are still able to hold a normal conversation.
- fast walking
- using a step-trainer or similar at gym
Choose physical activities that you enjoy, as you are more likely to continue doing them.
It is probably unrealistic to meet these exercise targets immediately if you have not exercised much in the past. So you should aim to start gradually – possibly 15 to 20 minutes of exercise five times a week – and then build on it.
If you are overweight or obese it is recommended you try to achieve a healthy weight.
This can be safely done through a combination of eating a healthy calorie-controlled diet and regular exercise.
It is normally recommended you aim for a body mass index (BMI)of less than 25 (but do not go lower than a BMI of 18.5 as this would be considered underweight).
Alcohol, drugs and medications
Regularly drinking alcohol above limits recommended will raise your blood pressure, which can be dangerous in people with a kidney transplant.
Therefore, staying within the recommended levels is the best way to reduce your risk of developing high blood pressure. The recommended limits for alcohol consumption are:
- 3-4 units a day for men
- 2-3 units a day for women
Alcohol is also high in calories, so you will gain weight if you drink regularly. Being overweight will also increase your blood pressure. .
You should avoid taking any illegal drugs as they can:
- damage your kidneys
- cause a sudden rise in blood pressure
- react unpredictably with your immunosuppressive medications
Finally, always check with your care team before taking any medication, including over-the-counter medication and herbal remedies such as St John's wort. These types of medications could be potentially dangerous.
Avoiding exposure to infection
Taking immunosuppressive medications on a long-term basis will weaken your immune system. Having a weakened immune system is known as being immunocompromised.
If you are immunocompromised, you will need to take extra precautions against infection.
Follow the advice below:
- Practise good personal hygiene. Avoid contact with people with serious infections, such as chickenpox or influenza (flu).
- Wash your hands regularly with soap and hot water, particularly after going to the toilet and before preparing food and eating meals.
- Take extra care not to cut or graze your skin. If you do, clean the area thoroughly with warm water, dry it, then cover it with a sterile dressing.
Be aware of any initial signs that you may have an infection. A minor infection could quickly turn into a major one.
Immediately report any possible symptoms of an infection to your doctor or transplant centre. Prompt treatment may be required to prevent serious complications developing.
Symptoms of infection include:
- high temperature (fever) of 38C (100.4F) or above
- aching muscles
Also ensure your vaccinations are up to date; though you will not be able to use any vaccines that contain live viruses such as the mumps, measles and rubella (MMR) vaccine.
Double kidney transplant recipient Riminder Dosanjh spent four years waiting for a transplant with no kidneys in her body at all.
"I was totally dependent on a dialysis machine for four years, just waiting and hoping every day for a new kidney," says Riminder.
"It was a terrible feeling to know that I had no kidney at all in my body and that I was 100% dependent on a machine to keep me alive. I was on the machine three times a week. It was horrible, really tough."
Riminder, a community health project worker, had her first kidney transplant when she was just four years old, after her own kidneys failed. But 14 years later, the transplanted organ also failed and had to be removed.
Riminder's natural kidneys, which were originally left in her body, were also removed to reduce dangerously high blood pressure. She was without any kidneys and totally dependent on a machine for life.
"Dialysis was dreadful after I had grown up through a perfectly normal childhood with a transplanted kidney. I had never prepared myself for my new kidney letting me down. I had been given a gift, but it had been snatched away."
In January 1997, Riminder was placed on the waiting list for a kidney transplant. She began to count the days until an organ would become available for her. Her family watched with ever-growing concern as complication after complication arose with her life-preserving dialysis treatment.
"I was getting some pretty serious complications with my dialysis. My veins were not strong enough and doctors had run out of space on my arm to link me to the dialysis machine. The treatment wasn't working properly at all and I was becoming desperate for a transplant," she said.
"This made me even more determined to get on with my life, to carry on working and make people accept me for who I am. I didn't want to be known as the one who was ill.
"I was hooked up to the machine one day and a doctor came and asked me whether I wanted a new kidney. I was whisked off to Hammersmith Hospital and woke up with a new kidney and a new life. But it didn't hit me until much later that I had finally got my life back."
That was in December 2000, and Riminder's life has improved ever since. Now fully fit, she works as a development officer and is active in promoting organ donation.
She says: "I can't express how grateful I am to the donor. I only know that it was a 55-year-old man. I'd like to know more but that's all the family want me to know, which is OK.
"I would love more Asian people to sign up to be organ donors to save people like me.”
When should a kidney transplant be performed?
Ideally, a kidney transplant should be performed when testing shows the extent of damage to your kidney is so great you will require dialysis within six months due to kidney failure.
However, due to the lack of available kidneys, it is highly unlikely you will receive a kidney donation at this time, unless a family member or friend who has a similar tissue type to you is willing to make a living donation.
Most people with kidney failure need dialysis while they wait for a donated kidney to become available. Usually, only one transplant in 10 is performed on people not on dialysis.
The average time that a person spends on the waiting list for a kidney transplant is two years.
Those with rarer blood groups tend to wait longer than people with more common blood groups.
Waiting for a transplant
The transplant centre will need to contact you at short notice, so you must inform staff if there are any changes to your personal contact details.
You should also inform staff if there are changes to your health, for example, if you develop an infection.
While waiting for a donated kidney to become available, it is important you stay as healthy as possible by doing the following:
- eat a healthy diet
- take regular exercise if possible
- moderate your consumption of alcohol – recommended limits for alcohol consumption are 3-4 units a day for men and 2-3 units a day for women;
- if you smoke, quit! For more information about giving up smoking, see treatment for quitting smoking
Prepare an overnight bag and make arrangements with friends, family and work so you can go to the transplant centre as soon as a donor becomes available.
Who can use a kidney transplant?
Most people are able to have a kidney transplant, regardless of their age, as long as they are:
- well enough to withstand the affects of surgery, and
- the transplant has a relatively good chance of success, and
- a person is willing to comply with the recommended treatments required after the transplant – such as taking immunosuppressant medications and attending regular follow-up appointments
Reasons why it may not be safe or effective to perform a transplant include:
- cancer that has spread to several places in your body (metastatic cancer)
- an ongoing infection – the infection will need to be successfully treated before a transplant can take place
- severe heart disease
- liver failure – where your liver is unable to function properly as a result of damage or disease, such as scarring of the liver (cirrhosis)
- AIDS, which is the final and most serious stage of an HIV infection (due to your vulnerability to infection, it would be too dangerous to weaken your immune system after surgery to prevent your body rejecting the kidney)
People who have HIV that is being effectively controlled with medication can often have a kidney transplant.
Why is a kidney transplant carried out?
End stage kidney disease (also known as kidney failure) is the most common reason for having a kidney transplant.
The kidneys contain millions of tiny filters, known as nephrons. As blood passes through the kidneys, nephrons filter out excess fluid and waste products. These are released from the body in urine.
However, if the nephrons become damaged, the kidneys can lose their filtering abilities and dangerous levels of fluid and waste products can build up.
When the kidneys have lost around 90% of their filtering ability, the person is said to have end stage kidney disease.
The two most common causes of end stage kidney disease are:
- diabetes: high blood glucose levels associated with diabetes can damage the filters in the kidneys, leading to chronic (long-term) kidney damage
- high blood pressure (hypertension): hypertension causes damage by putting strain on the small blood vessels in the kidneys, which prevents the filtering process from working properly
Less common causes of end stage kidney disease include:
- blockages in the arteries that bring blood to the kidneys
- polycystic kidney disease (an inherited condition where the kidneys become enlarged due to multiple cysts)
- undeveloped kidneys at birth
- autoimmune diseases that affect the kidneys such as systemic lupus erythematosus (a condition where the body attacks the kidney as if it were foreign tissue)
If end stage kidney disease is not treated, the amount of waste products in the blood will build up to a dangerous level, resulting in coma (unconsciousness) followed by death.
There are two main treatment options when it is known kidney failure is likely to occur:
- dialysis, where a mechanical device is used to replicate the functions of the kidney
- kidney transplant, which, if possible, is usually the preferred option because it is much less inconvenient than having dialysis