Patient education: Hypovolemia in adults (The Basics)

What is hypovolemia? — This means that the body has lost too much water and salt (sodium). Sodium is a substance called an "electrolyte." Normally, the body has a specific balance of electrolytes. This is important to keep the cells working normally.

People often use the term "dehydration" when they mean hypovolemia. This is not exactly right. The 2 terms describe different types of fluid loss:

●Hypovolemia – This means loss of water and salt. Doctors also call it "volume depletion." This can happen if you have a lot of vomiting, diarrhea, or heavy sweating. If you can't take in enough fluids and salt to make up for what your body has lost, it can lead to problems.

●Dehydration – This means loss of water only, or not getting enough water to balance the body's salt. This can happen if a person has a health condition that makes them urinate much more than usual, so too much water is lost. It can also happen if a person does not drink enough water to make up for what their body loses normally.

It's important for doctors to know which type of fluid loss a person has. That's because they are treated in different ways.

What causes hypovolemia? — It's normal for people to lose some water and salt every day, for example, through urine and bowel movements. But some things make people lose a lot of water and salt. These include:

●Vomiting

●Diarrhea

●Sweating a lot, for example, from heavy exercise in hot weather

●Medicines that cause a person to urinate more than usual, called "diuretics"

What are the symptoms of hypovolemia? — Early symptoms can include:

●Feeling very tired

●Thirst

●Muscle cramps

●Dry mouth

●Skin that is less elastic than usual (for example, does not flatten out right away after you pinch it)

●Feeling dizzy when you stand up

●Urinating less often than usual

If hypovolemia is severe, it can cause other symptoms, such as:

●Belly pain

●Chest pain

●Confusion

Should I see a doctor or nurse? — If you have lost a lot of fluid and have any of the above symptoms, contact your doctor or nurse. They can tell you if you need to be seen.

Call for emergency help (in the US and Canada, call 9-1-1) if:

●You feel very weak, like you can't stand up, and your skin is cool, is clammy, or looks blue or gray.

●You have severe belly pain.

●You have chest pain or trouble breathing.

●You pass out.

●You do not urinate for more than 8 hours.

Is there a test for hypovolemia? — Yes. Your doctor or nurse can do blood and urine tests to check for this. They will also do an exam and ask about your symptoms.

How is hypovolemia treated? — Hypovolemia sometimes gets better on its own once you stop losing water and salt.

If you do need treatment, this involves giving your body water and salt to make up for what it has lost. In mild cases, you might be able to do this on your own by:

●Drinking liquids that contain salt – Examples include "oral rehydration solutions," sports drinks, and broth. Try drinking small amounts every 15 to 30 minutes.

●Eating when you are able – Good choices include lean meats, fruits, vegetables, and whole-grain breads and cereals. If you drink a lot of plain water, it's especially important to make sure you are also eating. This will help your body keep the right salt and water balance.

Some people follow a low-salt diet, for example, to help control their blood pressure. If you normally limit or avoid salt, stop doing this while you recover from hypovolemia. It's important to replace the salt your body has lost. Your doctor can tell you when to go back to your usual diet.

In more severe cases, you might need treatment in the hospital. This involves getting fluids through a thin tube that goes into a vein, called an "IV." This helps get your body's level of water and salt back to normal.

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