Hyponatremia is a condition that occurs when the level of sodium in your blood is abnormally low.
Sodium is an electrolyte, and it helps regulate the amount of water that's in and around your cells. In hyponatremia, one or more factors — ranging from an underlying medical condition to drinking too much water during endurance sports — causes the sodium in your body to become diluted. When this happens, your body's water levels rise, and your cells begin to swell. This swelling can cause many health problems, from mild to severe.
Hyponatremia treatment is aimed at resolving the underlying condition. Depending on the cause of hyponatremia, you may simply need to cut back on how much you drink. In other cases of hyponatremia, you may need intravenous fluids and medications.
Hyponatremia signs and symptoms may include:
When to see a doctor
Sodium plays a key role in your body. It helps maintain normal blood pressure, supports the work of your nerves and muscles, and regulates your body's fluid balance.
When the sodium level in your blood becomes too low, extra water enters your cells and causes them to swell. Swelling in your brain is especially dangerous because the brain is confined by your skull and unable to expand without causing symptoms.
Types of hyponatremia
The imbalance between sodium and water in your blood may occur in three primary ways:
Causes of hyponatremia
The following factors may increase your risk of hyponatremia:
In chronic hyponatremia, sodium levels drop gradually over days or weeks — and symptoms and complications are typically more moderate.
In acute hyponatremia, sodium levels drop rapidly — resulting in potentially dangerous effects, such as rapid brain swelling, which can result in coma and death.
Premenopausal women appear to be at the greatest risk of hyponatremia-related brain damage. This may be related to the effect of women's sex hormones on the body's ability to balance sodium levels.
Preparing for your appointment
Seek emergency care for anyone who is at risk of hyponatremia — due to prolonged athletic activity, an underlying medical condition or use of the drug Ecstasy — and develops severe signs and symptoms, such as nausea and vomiting, confusion, seizures or lost consciousness.
Call your doctor if you are at risk of hyponatremia and are experiencing nausea, headache, cramping or weakness. Depending on the extent and duration of these signs and symptoms, your doctor may recommend seeking immediate medical care.
If you have time to prepare, here's some information to help you get ready for your appointment, and what to expect from your doctor.
What you can do
For hyponatremia, some basic questions to ask your doctor include:
What to expect from your doctor
Tests and diagnosis
Your doctor will start by asking about your medical history and doing a physical examination.
However, because the signs and symptoms of hyponatremia occur in many conditions, it's impossible to diagnose the condition based on a physical exam alone. To confirm low blood sodium, your doctor will order blood tests and urine tests.
Treatments and drugs
Hyponatremia treatment is aimed at addressing the underlying cause, if possible.
If you have moderate, chronic hyponatremia due to your diet, diuretics or drinking too much water, your doctor may recommend temporarily cutting back on fluids. He or she also may suggest adjusting your diuretic use to increase the level of sodium in your blood.
If you have severe, acute hyponatremia, you'll need more aggressive treatment. Options include:
The following measures may help you prevent hyponatremia:
Last Updated: 2011-07-14
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