Fluid, a guide to getting the balance right

What is fluid balance?

The kidneys play an important role in controlling the amount of fluid in the body. They do this by removing any excess fluid in the form of urine.

Depending on your level of kidney function, you may be passing more or less urine than usual. If you drink more fluid than you pass, then the excess fluid may build up in your body. This is called fluid overload. If you drink less fluid than you pass, the normal water content of your body may reduce. This is called dehydration.

Your doctor may ask you to drink more or less fluid depending on your treatment, symptoms and urine output.

How do I know if I am fluid overloaded?

If you have too much fluid in your body you may experience the following symptoms:

• Sudden increase in weight e.g. over 1 kg (= 2.2 lbs) in a day
• Swelling, particularly in the ankles, hands and around the eyes
• Shortness of breath
• High blood pressure

What happens if I become fluid overloaded?

Having too much fluid in your body can cause health problems, including the following:

• Fluid may remain in the lungs making it difficult to breathe and may lead to chest infections
• High blood pressure can put a strain on the heart and make the heart muscles weak. This may increase the risk of stroke or heart attack

If you are fluid overloaded, your doctor may ask you to drink less fluid because it is building up in your body. This is due to your kidneys not managing to remove all the fluid that you are drinking. You may be prescribed a tablet called a diuretic (water tablet) to help reduce the fluid that has accumulated and improve your symptoms. Examples of diuretic tablets include furosemide and bumetanide.

How do I know if I am dehydrated?

If you are not drinking enough fluid, you may experience the following symptoms:

• Headaches
• Low blood pressure
• Producing small amounts of dark, strong smelling urine
• Feeling light headed
• Feeling tired and confused

What happens if I become dehydrated?

If you do not drink enough fluid you may become dehydrated. This changes the balance of minerals and waste products in the body, which affects how it functions. If you are dehydrated for a long time it can cause damage to your kidneys.

If you are at risk of becoming dehydrated, your doctor may ask you to drink more fluid. In this case, it is important to drink the recommended amount of fluid to avoid damage to your kidneys.

Your recommended fluid intake may change depending on your symptoms and treatment so make sure to ask your doctor or dietitian if you are unsure.

What if I am on dialysis?

Haemodialysis

If you are on haemodialysis please refer to the booklet ‘Fluid management on haemodialysis’ for further information.

Peritoneal dialysis

Fluid may be removed more often with peritoneal dialysis compared to haemodialysis. However, there is still a limit on how much fluid can be removed each day.

When on peritoneal dialysis you are advised to weigh yourself daily. The aim is to keep your weight within 0.5 kg of your target weight, which will be set by the peritoneal dialysis team. The team will advise you on how much fluid you should drink in order to maintain this

What if I have had a kidney transplant?

You may have been advised to drink more fluid following your transplant. This may be difficult if you were used to drinking less. There are some tips to help increase your fluid intake later on in this booklet.
Your recommended fluid intake may sometimes change following your kidney transplant. It is important to speak with your doctor, transplant nurse or dietitian if you are unsure how much fluid to drink.

Measuring your fluid intake

It is a good idea to measure the amount of fluid you are drinking. This will help to make sure you are meeting your recommended fluid intake.

When counting fluids, remember to include all drinks, including milk on cereal and water taken with tablets.

This list can be used as a guide to help you measure your fluid intake. You may find your own cups and serving sizes vary at home so we recommend you measure them.

Example:

• 1 tea cup – 200 ml
• ½ tea cup – 100 ml
• 1 mug – 300 ml
• 1 tall tumbler – 250 ml
• 1 small wine glass – 125 ml
• 1 can fizzy drink – 330 ml
• 1 small can fizzy drink – 150 ml
• 1 pint – 568 ml
• ½ pint – 284 ml
• 1 pub measure spirits – 25 ml
• 1 ice cube – 20 ml
• Milk just covering cereal – 100 ml
• Ice lolly – 70 ml

Remember that food contains fluid. The following foods do not need to be avoided (unless advised by your dietitian).

However, if you need to restrict your fluid intake further, you may be advised to count the following as part of your fluid intake for the day.

• 1 portion of milk pudding – 150 ml
• 1 portion of custard – 100 ml
• 1 portion of jelly – 100 ml
• 1 carton of yoghurt – 125 ml
• 1 scoop / brickette of ice cream – 50 ml
• 1 portion of stew or casserole – 100 ml
• 1 portion of savoury sauce – 50 ml
• 1 tablespoon gravy – 15 ml

You do not need to count the fluid in rice, pasta, fruit, vegetables, salad or potatoes.

Tips to help reduce your fluid intake

• Ask the dietitian for more information about reducing the salt in your diet
• Try to drink when thirsty rather than out of habit
• Measure how much fluid your cup holds
• Try using a smaller cup or try drinking only half cups
• Try to take medication with mealtime fluids unless advised otherwise
• Stimulate production of saliva by:
  • Sucking on an icecube or a lemon wedge
  • Sucking mints, sherbet, acid drops, or boiled sweets
  • Chewing gum

• Use mouthwash or cold water to rinse out your mouth, but do not swallow
• If you have diabetes, aim to keep your blood sugars well controlled as this will help to control your thirst

Tips to help increase your fluid intake:

• Try to include small, but frequent drinks throughout the day. Consider setting regular reminders on your phone to prompt you to take a drink
• Take a drink with you when you go out
• Have foods which have a high fluid content, such as jellies, ice cream and lollies
• Add sugar-free squash to water to add flavour

Monitoring your fluid intake

If you have been asked to measure your fluid intake, please select the below link to the fluid diary, this can be saved and used to record your intake.

Fluid – Diary (692kB pdf)

Summary

• It is important to avoid fluid overload and dehydration in the short and long term
• Keep to your recommended fluid intake as advised by your doctor or dietitian
• Measure your own cups and glasses at home to keep track of your fluid intake

Do not hesitate to ask your dietitian if you would like further recipe ideas or if you require more information regarding a reduced salt diet.

If you have any suggestions or comments regarding this leaflet please let your dietitian know.

Useful websites and reading: