Your Child & Chronic Kidney Disease - 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.
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.
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.