Fluids and Dialysis

Dry weight is your child’s weight with the right balance of fluid.

One way to measure the amount of fluid in the body is to keep track of your child’s weight. The total weight is made up of: body weight and fluid weight.

Body weight is all the solid things in the body like bones, muscles, and fat. Body weight should increase as your child grows.

Fluid weight is the part of the body that is liquid, not solid. The body tissues are full of liquid, and the blood is liquid. Fluid weight increases when your child drinks liquids. For example, a 2-liter bottle of soda weighs 2 kilograms (kg). If your child drinks the entire bottle, their weight will increase by 2 kg.

Healthy kidneys balance the amount of fluid in the body by making urine. When your child takes in more than their body needs, the kidneys will get rid of the extra fluid by making a large amount of urine. When they take in a small amount of fluid, the kidneys will concentrate, or hold onto water and make less urine. This is how body water is controlled and your ideal, or dry weight, is maintained.

When the kidneys fail, the body is unable to make or hold onto the right amount of water for the body. Fluid control in kidney failure is important for your child’s overall health and will also make dialysis treatments more comfortable. Your child’s nephrologist (kidney doctor) will talk with you about how much liquid they can have in between treatments.

The terms “fluid overload” or being “heavy” are used when your child has too much fluid in the body. When there is extra fluid in the blood, the heart has to work harder to pump the blood through the vessels. This puts a strain on the heart and other organs. Some of the signs of fluid overload are:

• Edema (Puffiness) – The extra fluid builds up inside the bloodstream. Then some of the fluid moves into the tissues under the skin. This is called “edema.” You will usually see puffiness around the eyes, fingers, and ankles.
• Cough and shortness of breath – Extra fluid can also go to the lungs. This will cause your child to feel tired and out of breath and they may have a bad cough. It may be hard to breathe if they lay down. If your child is having these problems at any time, call the dialysis unit or the nephrologist, or go to the emergency room.
• High blood pressure (hypertension) –The extra fluid in the bloodstream causes the blood pressure to go higher. The heart must work harder to pump around the extra fluid. At first, the heart will build up the muscle in the heart wall so it can pump better. But if the heart must keep pumping extra fluid, the muscle becomes too thick and cannot work well. Over time this leads to damage of the heart muscle. Even young people on dialysis can have heart failure because of drinking too much fluid between dialysis treatments.

Failing kidneys may still make a lot of urine whether the body needs it or not. Failing kidneys can make so much urine that your child can become dehydrated (when the body loses more fluid than you are taking in). Sweating, vomiting, and diarrhea may also cause dehydration.

Your child may be dehydrated if they have any of these signs and symptoms:

• Dizziness
• Nausea and vomiting
• Low blood pressure
• Weighing below their dry weight
• Weakness
• Sunken, dark eyes
• Muscle cramping

Call the dialysis nurse or nephrologist if your child is having any of these symptoms.

During dialysis the fluid can only be removed from the blood vessels. The fluid in the tissues cannot shift to the blood vessels as fast as it is removed from the blood. This will cause your child’s blood pressure to drop, and they may have muscle cramps, nausea, vomiting or headache.

If your child has these symptoms, it does not mean that all of the fluid has been removed (gotten to their dry weight). It means that the fluid hasn’t shifted from the tissues yet and they are still heavy.