Healthy Hydration and Your Kidneys

Healthy hydration (hi-dray-shun) means that you have the right amount of water in your body to maintain good health. In other words, you are well hydrated (hi-dray-ted).  Too little water in your body is called dehydration (de-hi-dray-shun).  You can also have too much water in your body.  This is called fluid overload.  Most body fluids, like blood, contain water.

Your body can usually maintain healthy hydration because:

• Your kidneys make your body hold on to water when you need it. 
• Your kidneys also make urine (pee) so water can’t build up in your body. 
• Your kidneys and brain make you thirsty when your body needs more water.  That’s how you know to drink more fluids to stay well hydrated. 

More than half of your body is made of water.  And all parts of your body need water to work well. That includes your kidneys.

• Water helps the kidneys to remove waste from your blood in the form of urine.
• Water also helps blood vessels stay open. Then blood can move through the blood vessels to carry nutrients to your kidneys.
• If you become dehydrated, then blood and nutrients can’t get to your kidneys. This can happen with severe dehydration.
• Severe dehydration can lead to kidney damage. So, it's important to drink enough when you work or exercise very hard, and especially in hot and humid weather.

Kidney stones and urinary tract infections (UTIs) can harm the kidneys, but drinking extra water can be helpful.

• Kidney stones form less easily when there’s enough water to stop stone-forming crystals from sticking together.
• Water helps break down medicines used for UTIs, so they work better. Water also helps make more urine to flush out germs that can harm the kidneys.

You may need to limit fluids if you have advanced chronic kidney disease (CKD) or have kidney failure. This includes people who are on dialysis. This is because you’re making little or no urine.  This causes water to build up in the body.  This leads to:

• Swelling (edema) in the feet, ankles, hands, face, and lower back
• Shortness of breath
• Cramping
• Headaches
• High blood pressure
• Stress on the heart

Therefore, it’s very important to limit fluids to the amount your healthcare team says is safe.  The Dos and Don’ts of Fluid Management for Kidney Disease

You often hear that you should drink eight cups of water a day.  But there’s no rule that everyone should have that amount.  For most people without CKD or kidney failure, your daily water needs depend on:

• Age
• Size
• Climate 
• Exercise level
• Pregnancy or breastfeeding
• Illness, especially vomiting and diarrhea

Healthy hydration is possible for most everyone with these fluids and foods:

• Water
• Cow’s milk
• Almond milk and milks from other plants
• Unsweetened fruit juices
• Soups and foods with high water content 

Older people often don’t have a good sense of thirst, so you may need to give them more fluid than they would take on their own.  Their urine also has more water in it, and certain medicines can make that even worse. This can lead to problems like UTIs. 

In some cases, it can be harmful to drink too much water. This happens during sports when people drink large amounts of water. The extra water makes salt in the blood go too low. This can harm the brain and even cause death. This has happened to people on TikTok who drink too much water too fast. This can also happen with medicines that cause you to hold onto water.

1. What are my daily fluid needs?
2. Are there reasons why I might need to have extra daily fluid?
3. Do I need to limit my daily fluid intake because of my kidney disease?
4. If I need to limit my daily fluid, what amount should I have?
5. Can you refer me to a registered dietitian nutritionist (RDN) who can help me manage my fluid intake?

This content is provided for informational use only and is not intended as medical advice or as a substitute for the medical advice of a healthcare professional.