Managing your fluid and salt levels

If you have been advised to reduce the amount of fluid you drink, it is important to also reduce the amount of salt in your diet. Read our guide to cutting down on salt and managing your fluid intake; ask your kidney team for support and personalised advice.

This information is aimed at people who have problems with their kidneys and have been advised by their kidney doctor, nurse or dietitian to control the amount of fluid that they drink.

Not everyone with a kidney condition needs to reduce their fluid intake so it is important to check with your kidney team before you follow the advice on this page.

Managing a fluid allowance: what counts as fluid?

All liquids that you / your child drink(s), including drinks taken with medications, need to be counted.

Fluid foods such as soup, gravy, custard, jelly and porridge also need to be included in your fluid allowance.

Solid foods such as fruit and vegetables are not counted.

Why do I need to the control the amount of fluid I / my child drink(s)?

One of the key jobs of healthy kidneys is to control the amount of fluid in your body. This is known as fluid balance. Excess water normally passes out of the body as urine. However if you have problems with your kidneys they may be unable to stop extra fluid from building up.

This is known as fluid overload.

How can fluid overload cause problems?

Fluid overload can cause the body to swell. You may notice this first around the ankles and in the legs. It can also put a strain on the heart and lungs, causing problems such as:

  • High blood pressure
  • Breathlessness due to fluid on the lungs
  • Chest pain/angina
  • Swelling of ankles, hands or eyes
  • Headaches

At the other extreme, not drinking enough fluid, or losing too much due to sickness or diarrhoea, can also cause problems as it can result in dehydration. It is therefore important to maintain the right fluid balance.

How much can I / my child drink as part of a fluid allowance?

Your kidney doctor, nurse or dietitian will advise you on the amount of fluid that you should consume on a daily basis to keep in the best condition of health. This is known as your fluid allowance.

Your fluid allowance will depend on a number of factors, including:

  • The stage of kidney disease
  • The type of treatment you are having, e.g. dialysis
  • Blood pressure
  • Weight
  • Whether you / your child are showing signs of fluid retention
  • How much urine you / your child pass daily

Everyone’s fluid allowance is different. You / your child may be advised to drink more or less than another patient, even if they are on the same form of treatment. Your own fluid allowance may change over time as treatment progresses. You may be asked to measure the amount of urine that you / your child pass in a day to help calculate your fluid balance. In general, the more urine you produce, the more fluid you can drink.

How can I monitor my fluid allowance?

If you are in hospital, your fluid allowance will likely be monitored for you by your kidney doctor or nurse. They will record how much fluid you have had each day on your fluid balance chart. You can use this chart to keep track of your own progress.

You / your child will generally be weighed each day as your kidney doctor can monitor how much fluid you are losing by checking to see how your weight changes. Your weight will go down by 1kg for every litre of excess fluid that your body gets rid of.

If you are at home you will need to monitor your own fluid allowance, with the help of your kidney team. You may like to create your own fluid balance chart so you can keep track of how much you fluid you have each day. Your dietitian can help you with this.

It is important to try and keep to your recommended fluid allowance as best as you can as it has been calculated to keep you in the best condition of health.

How can I control my fluid allowance?

You may find it hard to keep to your fluid allowance at first, especially if you have to limit the amount of fluid that you drink. It is important to discuss any concerns you may have with you kidney doctor, nurse or dietitian. The following tips may also help:

Measure your fluid allowance into a jug at the start of the day. Every time you drink, take that amount of volume away from the jug so you know what you have left to drink

  • Use a small cup and spread your drinks throughout the day
  • Take small sips rather than big gulps of fluid
  • Freeze a drink in a plastic bottle and sip it as it defrosts
  • Suck on ice cubes as they last longer than water. Try freezing them with fruit squash
  • Chew sugar free gum, suck on boiled sweets or aqua drops
  • Rinse your mouth with mouthwash
  • Choose cold rather than hot drinks to quench your thirst
  • Take tablets with food instead of water
  • For extra support, tell your friends and relatives that you are on a fluid allowance

How can I reduce my salt intake?

A high amount of salt in your diet can make you feel thirsty which may make you drink more than you have been advised.

The following tips will help you reduce the amount of salt in your diet:

  • Avoid adding salt at the table.
  • Avoid very salty foods e.g. burgers, sausages, bacon, cheese, smoked fish, crisps, salted biscuits.
  • Avoid tinned soup as these are high in salt and contribute to your daily fluid allowance
  • Try to cut down on ready-made meals, packet sauces and sauces in jars as well as takeaways. Replace these with home-made foods where possible.
  • Experiment with other seasonings such as herbs, spices, garlic, vinegar, pepper.
  • Limit your use of stock cubes as these are very salty
  • Check food labels – foods with more than 1.5g salt or more ‘per 100g’are high in salt. Look for alternatives or choose less of these. ‘Lo salt’ products are not be suitable as they contain a salt substitute, potassium which can be harmful for people with kidney disease.

How much fluid is in...?

Remember everything that is liquid or semi-liquid counts towards your fluid allowance.

Fluid measurements