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Low sodium (hyponatraemia)

Sodium is an important electrolyte that helps keep the right amount of water in and around your cells. It's also needed for your nerve and muscle function.

Low sodium (hyponatraemia) is when the concentration of sodium in your blood is below the normal range (135-145 mEq/L).

Low sodium can cause swelling within your cells leading to problems that can range from mild to serious and even life threatening.

You have an increased risk of getting low sodium as you get older, especially if you have a heart or kidney condition and take certain types of medications.

Causes of low sodium

Reasons why your sodium level might get too low include:

Symptoms of low sodium

You may not have any symptoms if your low sodium is mild. You're more likely to have symptoms if your sodium drops quickly or is very low.

Signs of low sodium may include:

Diagnosing low sodium

Because the symptoms of low sodium can vary so much from person to person, a blood test is needed to make the diagnosis. You may also need a urine test.

A routine blood test that you have for other reasons may also show low sodium.

Treating low sodium

Your treatment will depend on how severe your low sodium is and what the likely cause is.

You may be asked to cut back on how much you drink.

Other treatments aim to correct the underlying problem and may include stopping any medication that can lower your sodium.

If your sodium level is very low, you may need treatment in hospital to boost your sodium level with careful monitoring.

Preventing low sodium

There are several ways you may be able to prevent low sodium:

Written by HealthInfo clinical advisers. Page created September 2022.

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Review key: HILSO-1048477