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What do the kidneys do?

The kidneys are reddish brown organs about the size of their owner’s fists. They lie either side of the back bone just below the ribs protected by all the muscles of the back. Although most people are born with two kidneys, one is enough to meet the body’s needs.

The kidneys are attached to the bladder by thin tubes called ureters as you can see in the diagram (right). The tube leading from the bladder to the outside of the body is known as the urethra. The kidneys receive their blood supply from the main blood vessel of the body known as the aorta.

When you eat or drink, the excess water and the waste products of digestion are filtered from the blood by the kidney to produce urine. Kidneys also produce hormones which help to control blood pressure, growth of bones and the production of red blood cells.

What is chronic kidney disease?

There are many different causes of chronic kidney disease and your child’s condition will be discussed with you by the doctor who is a kidney specialist (nephrologist).

In chronic kidney disease there is a slow build up of waste products and sometimes fluid in the body. At first the effects of this can be helped by careful attention to the diet and the use of medicines. You may sometimes hear people call this conservative or pre-dialysis treatment. During this time, which may last for several years, your child will have regular assessments and investigations to see how well the kidneys are working.

However, when the build up of waste products increases such that your child’s health shows signs of being affected, then dialysis and/or kidney transplantation become necessary.

Stages of chronic kidney disease

There are 5 stages of chronic kidney disease. These are divided up according to the GFR (glomerular filteration rate). The GFR can be estimated from the child’s height and blood test results or family measured as a day case on a ward. The GFR is approximates to the percentage of overall kidney function. The 5 stages are shown in the table below.

Stage GFR/Percentage Kidney Function Description
1 90+ Normal kidney function but urine tests or other abnormalities point to kidney disease
2 60-90 Mildly reduced kidney function
3 30-60 Moderately reduced kidney function
4 15-30 Severely reduced kidney function
5 <15 Very severe or established renal failure, dialysis or transplantation needed at this stage

What a kidney investigations?

After your child has been diagnosed with chronic kidney disease, he/she will be seen at regular intervals in the outpatient clinic.

Height, weight and blood pressure will be checked at the clinic. The nephrologist uses these results along with urine and blood tests to see how the kidneys are working.

A sample of urine, preferably taken first thing in the morning and brought to the clinic will be required for testing for protein. The build up of waste in the blood needs to be checked by blood tests. Naturally many children (and adults) are worried about needles, so, whenever possible a special cream or spray is used which can help numb the skin where the needle is going to be placed. The cream needs to be put on before the blood test is taken. The freezing spray can be used immediately.

Play preparation, stories and other methods can be used to prepare your child for any tests. Please ask the nursing or unit staff for advice or other information.

Occasionally your child may need to be admitted to the ward for a short stay in order to carry out more specialised tests. These may include:

    1. Glomerular filtration rate (GFR) which is an accurate measurement of the overall kidney function. This test is carried out to monitor treatment and can help us to predict when your child may require dialysis and /or kidney transplant.
    2. Renal biopsy - This is carried out if we are uncertain about the cause of the kidney failure. If a biopsy is necessary then the procedure will be fully explained to you.
    3. X-ray investigations - When your child is found to have chronic kidney disease he/she is likely to have a number of different tests performed in the x-ray department to investigate the problem. Most of these are carried out as an out patient. The most frequent one is an ultrasound examination which does not involve any needles or tubes.

Another x-ray used is to look at your child’s bones (usually hands and wrists) to see how they are growing.


Treatment is planned on a long term basis for each individual child. Regular exercise and normal school activities are always encouraged.

Is there a special diet?

Diet plays a very important part in the management of chronic kidney disease and the dietician will discuss this with you. The family may be asked on occasions to keep a diary of the child’s intake over three days in order that the diet can be assessed.

Why is diet important?

All children need a well balanced diet consisting of energy containing foods, proteins, vitamins and minerals in order to grow and develop into adults. Children with chronic renal failure have special requirements and need individual assessment. In general, energy intake may have to be increased and protein controlled.


Children require protein for growth and repair. Urea is a waste product of protein digestion and is filtered out of the body by the kidneys into the urine. As the kidney function gets worse, urea and other wastes build up in the blood and make the child unwell.

Before dialysis, the dietitian looks at each individual child’s diet and advises levels of protein intake to see that there is adequate protein for growth. Once dialysis has started the amount of protein required will depend upon the type and frequency of dialysis chosen.

There is usually no restriction on protein intake after a successful transplant.


Energy is provided in the diet from carbohydrates (sugars and starches) and fats. It is very important that enough energy giving foods are included in the diet. Energy supplements may be necessary when intake is poor.

Sodium (salt)

The kidneys control the amount of salt (sodium) the body needs and any excess is passed into the urine. When the kidneys are not working well sodium levels may build up in the body and cause thirst, puffiness (oedema) and possibly high blood pressure (hypertension). To prevent this you may be asked to reduce your child’s intake of salt. You can do this by not adding salt to food at the dining table. The dietitian will teach you how to read food labels in order to select lower salt foods.

There are some children who actually lose sodium in their urine. If this is the case then there will be no salt restriction and sodium supplements may be necessary.


Poor kidney function may cause an increase in the level of potassium in the blood. This can be dangerous as it can be harmful to the heart. It is important that foods high in potassium are avoided. The dietician’s advice will be tailored to each individual child’s level of kidney function and other treatment.

Calcium and phosphate

Calcium and phosphate are both important for the growth of strong bones.

In chronic kidney disease there is a build up of phosphate in the blood because the kidneys cannot excrete enough phosphate in the urine. There is also a lack of a very special form of vitamin D made by the kidneys. This can lead to a type of bone disease known as renal osteodystrophy. Importantly in the long term, it is known that an imbalance of calcium and phosphate can also cause heart problems. Attempts will be made to prevent these problems with low phosphate dietary advice and a medicine called phosphate binders. Calcium and phosphate and the level of a hormone called parathyroid hormone (PTH) are monitored.


The kidneys control fluid balance within the body. When the kidneys cannot get rid of excess water, fluid is held within the tissues causing weight gain, puffiness (oedema) and a rise in blood pressure (hypertension). If this happens it may be necessary to reduce the amount of fluid that your child drinks. Salty foods should also be reduced to avoid increasing thirst.

With some types of kidney disease, the kidneys produce large amounts of weak urine. In this case it may be necessary to encourage lots of fluid. Children with this type of problem are at risk of dehydration if they develop diarrhoea or vomiting.

Vitamins and minerals

Vitamins and minerals are essential for good health. A good balanced diet should provide adequate amounts.

Children with chronic kidney disease may have poor appetites and therefore may need a daily vitamin and sometimes mineral supplement. Some vitamins are lost during dialysis and these will also need to be replaced by a prescribed supplement.


Anaemia is a condition in which there is a reduction in the haemoglobin concentitia – the blood. The kidneys produce a hormone called erythropoietin (EPO) which helps the body to produce red blood cells. Children with chronic kidney disease can develop anaemia, the main symptoms are paleness and fatigue. Red blood cells contain iron, so we can treat the anaemia with iron supplements. Iron treatment can be given through the veins (we can give this treatment in clinic using the same needle that we use to take blood tests).

Some children will also need erythropoietin (EPO) treatment, this is given as a small injection, just under the skin.

Dietary supplements

There may be times when your child will need extra protein or energy in their diet. To achieve this, your doctor and dietician will decide upon a suitable nutrient rich supplement that can either be taken as a ready made drink or as a soluble powder in drinks. If dietary supplements are prescribed they should be treated with the same importance as medications.

Other methods of feeding

If your child’s appetite is poor and they are unable to take enough food and supplements to meet their special dietary requirements, it may be necessary to consider additional feeding in the form of tube feeding (gastrostomy or nasogatric). If this is required it will be discussed well in advance.

Diet and exercise following transplant

There is usually no dietary restriction following transplantation. However, it is important to avoid adding salt to food and reducing the number of salty snacks to help blood pressure control. Healthy eating and regular exercise which can be followed by all the family are always encouraged.

Medications for treating Kidney Disease

Various medicines or drugs are used in the treatment of chronic kidney disease. Each child has different requirements and these will be explained to you in more detail by your doctor at the hospital.

Important points

  1. Be sure you understand how the medicine should be taken.
  2. Do ask questions about what the medicines are for and what are the side effects.
  3. Some medicines are difficult to obtain. You should make sure you can get a supply either from the hospital or from the local pharmacist.
  4. You should have an up to date list of all the medicines that your child is on at all times. This is very important in the event of an emergency. Remember to take your list to clinic in case any changes need to be made.
  5. All patients with chronic kidney disease should carry an information card and consider a medic alert bracelet, particularly while on steroid drugs after a renal transplant.
  6. Make sure that other doctors and dentists who treat your child are aware of his/her medications.
  7. Paracetamol is the only recommended medicine for headaches or pain relief. Please contact your Renal Unit if other medicines are being considered.

Warning about medicines

  1. Dialysis and transplant patients must discuss other medicines, supplements or homeopathic remedies with their doctor.
  2. Prescribed drugs must be taken regularly as directed. If the prescribed times are inconvenient for school or family life please discuss this with your school or hospital doctor.
  3. Most drugs are released from the body through the kidney so many drugs may not be safe for patients with damaged kidneys.
  4. Parents should never allow a chemist to substitute another drug for one that is prescribed without first consulting the doctor.

Always keep medications in a safe place out of reach of young children.


Good dental care is essential and regular check ups at the dentist are advised

Playing and learning

Play is an important way of reducing the anxiety of hospitalisation for young children. In some wards, a play specialist may meet with the family and arrange suitable activities.

Specially designed dolls may be used to prepare children for many of the procedures such as starting dialysis or transplantation. These procedures become less frightening when they are explained through play.

It is very important to inform the child as fully as possible about their treatment and help them to develop their own coping strategies. This helps minimise any distressing effects of treatment.

Treatment options

When the kidneys can no longer remove enough of the waste products and excess water from the body some other way has to be found to do the work of the kidneys. Dialysis is a treatment which can help to do this until a kidney transplant becomes available. In some children it may be possible to consider preparing your child for a KIDNEY TRANSPLANT before dialysis becomes necessary. This is called a PRE-EMPTIVE TRANSPLANT.

When dialysis is necessary two main types are considered.

  • Peritoneal dialysis
  • Heamodialysis

The choice of dialysis for your child will be discussed with you after careful assessment. Peritoneal dialysis is usually carried out at home overnight whereas haemodialysis requires travel to the hospital several times a week.

Peritoneal dialysis

To be able to carry out peritoneal dialysis a soft tube (catheter) must be placed into the tummy (abdominal cavity) under general anaesthetic. The catheter does not enter a blood vessel and it must always be secured outside to the skin. The place where the catheter leaves the abdominal cavity (exit site) may be covered by a small dressing. The catheter is not painful but it may take a bit of getting used to at first.

How does chronic peritoneal dialysis work

Peritoneal dialysis uses the body’s own natural peritoneal membrane which lines the abdominal cavity. Dialysis fluid contains sterile water, salts and glucose (sugar). The fluid is run through the catheter into the abdomen and left to dwell. It draws out waste products and extra fluid from the blood vessels surrounding the peritoneal membrane which acts like a filter. After a certain amount of time the dialysis fluid is drained out through the same catheter and a fresh amount of fluid is run in to continue the process. This is what we understand by dialysis.

How can we manage this at home?

There are three different ways to carry out chronic peritoneal dialysis.

Automated peritoneal dialysis (APD)

This is carried out at home overnight by a machine while the child and family sleep. The machine carefully measures the amount of fluid which runs in and out of the abdomen each cycle. The exact number of cycles will be decided by the kidney specialist. In the morning the dialysis will be stopped and the catheter capped. Your child can then attend school or enjoy normal activities. It may be possible for your child to have one night free from dialysis during the week if he/she is passing urine.

Continuous ambulatory peritoneal dialysis (CAPD)

This method of dialysis is carried out by manual changes every 4 to 6 hours of dialysis fluid called bag changes. You will be taught how to connect a bag of dialysis fluid to the end of the catheter, run it in, leave to dwell and drain out. Again your child is free to enjoy normal activities and there should be no discomfort.

Intermittent peritoneal dialysis

This may be carried out two or three times a week in hospital, usually overnight while your child is sleeping. It is the least efficient form of peritoneal dialysis and is very rarely used these days except when it is not possible to dialyse at home or when your child does not require as much dialysis.


Dialysis using an artificial kidney outside the body is called haemodialysis. A machine is used to pump blood from the child to the artificial kidney and it is inside the artificial kidney where the dialysis takes place usually over three to four hours, several times a week. To perform this type of dialysis it is necessary to gain access to the blood stream so that the blood can be taken from and given back to the child. The type of access used will depend upon the age of the child and how long the dialysis will be needed.

To gain access to the blood vessels a special catheter is placed into one of the large veins in the neck and hidden under the skin so that only the end is exposed on the chest. Needles are not required for haemodialysis or blood sampling with this catheter. Since haemodialysis usually takes place in hospital your child will need to be accompanied to the hospital for these sessions. Education will be provided by the hospital school. In some older children a fistula is used for access. This requires an operation to connect in gently to a vein, usually in the forearm. This takes time to develop and is accessed using a needle.

Content compiled by members of the Children’s Renal & Urology Unit, QMC Campus, Nottingham University Hospitals.

The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.