Hyponatremia

Hyponatremia is when your blood sodium (salt) level is lower than it should be. Healthcare providers consider sodium (Na+) levels below 135 milliequivalents/liter (mEq/L) to be lower than normal.

It might seem like very little salt would be a good thing. But like many things in life, it’s all about balance. You need the right balance of water and sodium in your body to stay healthy. They can become unbalanced due to medical conditions or medications. When this happens, water moves into your tissues, causing them not to work properly. This can be especially dangerous in your brain.

If your kidneys are working as they should, drinking too much water almost never causes your blood sodium to fall too low unless you’re very dehydrated (like after running a marathon) and you don’t replace electrolytes (important minerals that keep your body working) at the same time.

Hyponatremia can be chronic or acute. Chronic hyponatremia can happen over a long time, with symptoms coming on slowly and your body making adjustments for the low sodium levels. With acute hyponatremia, blood sodium levels fall quickly, and your symptoms may become severe suddenly.

What are the types of hyponatremia?

Types of hyponatremia include:

• Euvolemic hyponatremia/dilutional hyponatremia. This is when the amount of sodium in your body stays the same but the amount of water in your body increases.
• Hypervolemic hyponatremia. This is when the amount of water and sodium in your body both increase, but the amount of water increases more.
• Hypovolemic hyponatremia. This is when the amount of water and sodium in your body both decrease, but the amount of sodium decreases more.

Knowing which type of hyponatremia you have helps your healthcare provider diagnose the cause and determine treatment.