What is hyponatremia?
Hyponatremia is a term for having a blood sodium level that is lower than normal. If you have blood tests, you’ll see it listed as “sodium” or “Na+” in your lab results.
Sodium and potassium levels in your blood are important. The correct ratio of these elements to the amount of total water in your body needs to stay in balance to make sure you stay healthy.
Actually, the main problem in a vast number of situations is too much water that dilutes the Na+ value. As a result, water moves into body cells, causing them to swell. This swelling causes a major problem in brain cells, which is a change in mental status that can progress to seizures or coma.
Many diseases and medications can cause hyponatremia. Most people recover fully with their healthcare provider’s help.
Unless your provider tells you something different, let your thirst be your guide in terms of how much water you drink.
Who is most at risk for hyponatremia?
Anyone can develop hyponatremia, but it is more likely to happen to people who:
- Have kidney failure.
- Have congestive heart failure.
- Have diseases that affect the lungs, liver or brain.
- Have conditions related to hormone levels and the endocrine system.
- Have had surgery.
- Take certain medications like some types of diuretics or some types of antidepressants.
How common is hyponatremia?
Hyponatremia is very common. It’s actually the most common chemical abnormality seen among people who are in the hospital and seen in outpatient clinics. Rates of hyponatremia are higher among people admitted to hospital care units or with the medical conditions mentioned earlier.
Symptoms and Causes
What causes hyponatremia?
In general, having too much water in your body is usually the main problem. The excess water dilutes the sodium levels. Much less frequently, hyponatremia is due to significant sodium loss from your body.
Too much water in your body causes your blood to become watered down. A good example is people who run in long races or run on hot days. They lose both salt and water in their sweat and often replace these losses with mostly water. This combination can be deadly because it dilutes the remaining sodium in the body.
It’s also possible to lose too much sodium from your body. Common causes include:
- Using diuretics: Diuretics can cause you to increase the amount of sodium you excrete in urine (pee). Some people even call diuretics “water pills.”
- Drinking too much alcohol: If you drink too much a lot of the time (chronic drinking) or binge-drink, you could pee more and lose fluid because you throw up.
- Untreated diarrhea: This can cause dehydration and hyponatremia.
- Taking certain medications: These include selective serotonin reuptake inhibitors (SSRIs) and carbamazepine (Tegretol®). SSRIs are commonly used to treat depression and carbamazepine to treat epilepsy and mania.
What are the signs and symptoms of hyponatremia?
Hyponatremia causes neurologic symptoms ranging from confusion to seizures to coma. The severity of the symptoms depends on how low the sodium levels are in the bloodstream and how quickly they fall. In many cases, blood sodium levels fall gradually, producing only mild symptoms as the body has time to make adjustments. Symptoms are more serious when blood sodium levels fall quickly.
Other signs and symptoms of moderate to severe hyponatremia include:
- Muscle cramps or weakness.
- Nausea and vomiting.
- Lethargy, or low energy.
- Mental status changes.
Hyponatremia is very dangerous for many organs, but especially for the brain.
Diagnosis and Tests
How is hyponatremia diagnosed?
Your provider will do a diagnostic workup if your blood sodium is low. The workup will include measuring urine sodium, potassium and creatinine concentrations. It will also include blood tests that indirectly show your total body water, your levels of sodium (Na+) and, in some case, levels of hormones that regulate water uptake by the kidneys. Your provider will also take a medical history and ask you questions, as well as do a physical exam. These steps will help them find out how low your sodium level is and why you have hyponatremia.
Your provider may ask you:
- What kind of sports you participate and how you train.
- What kind of prescription medications you take.
- What kind of medical conditions and surgeries you have or have had in the past.
- How much alcohol you drink, especially beer.
- Whether you take illegal substances like 3,4-methylenedioxymethamphetamine (MDMA, but also called Molly, E or Ecstasy).
Management and Treatment
How is hyponatremia treated?
You and your provider will work together to find the best treatment for the low blood sodium levels. Treatment depends on the underlying cause and the severity of your symptoms.
If you have mild symptoms, your provider makes small adjustments to correct the problem. Treatment may be short-term or long-term. A short-term treatment includes:
- Limiting water intake.
- Adjusting or stopping medications.
- Treating underlying causes.
A long-term treatment plan may include:
- Limiting water intake.
- Adjusting or stopping medications, or adding newer medications.
- Adding salt to your diet.
If you have moderate to severe hyponatremia, you probably will need to go to the hospital for thorough medical evaluation and treatment. People with most serious cases of hyponatremia will probably get replacement sodium intravenously (straight into a vein). They’ll also have to limit their water consumption.
Your provider may prescribe a medication like tolvaptan (Samsca®) or conivaptan (Vaprisol®) to correct blood sodium levels.
Are there complications associated with hyponatremia?
In many cases, hyponatremia causes extra water to move out of the bloodstream and into body cells, including brain cells. Severe hyponatremia causes this to occur quickly, resulting in swollen brain tissue. If left untreated, complications can include:
- Mental status changes.
Can I prevent hyponatremia?
If you have certain underlying medical conditions, you may be more likely to have low blood sodium levels. You can lower your risk for hyponatremia by following your treatment plan and restricting your water intake to levels recommended by your healthcare provider.
You should always tell your provider about any new symptoms right away. If your provider is monitoring your blood sodium levels, you’ll need to take blood tests.
Here are some tips that may help you prevent hyponatremia:
- Don’t drink too much beer and/or other forms of alcohol.
- Drink enough water, but not too much water.
- Don’t take MDMA.
- If you’re an athlete, don’t forget to include electrolytes when you’re hydrating during sporting events.
- Take care of yourself by managing your medical conditions consistently and well.
- Eat a balanced diet, including food with high value protein content.
Outlook / Prognosis
What are the outcomes after treatment for hyponatremia?
With treatment, many people recover fully from hyponatremia. Your healthcare provider can help even if you have long-term hyponatremia.
Older adults and people who are in the hospital for a long time may have worse outcomes.
When should I call my healthcare provider?
If you develop any symptoms of hyponatremia, contact your healthcare provider immediately. Hyponatremia can become an emergency if your sodium level falls too much or too quickly.
Frequently Asked Questions
Are there types of hyponatremia?
You may hear about different kinds of hyponatremia. Types include:
- Euvolemic hyponatremia: If the amount of sodium in your body stays the same, but your total body water increases, you have euvolemic hyponatremia.
- Hypervolemic hyponatremia: If the total body water increase is larger than the increase in total body sodium, you have hypervolemic hyponatremia.
- Hypovolemic hyponatremia: In this situation, the total body water decrease is bigger than the decrease in total body sodium.
- Dilutional hyponatremia: This type of low blood sodium is also called “water intoxication.” It refers to drinking too much water without including electrolytes that supply necessary minerals like calcium, potassium and sodium. Most people, unless they have conditions that put them at risk for hyponatremia (see above) would have to drink large amounts of water over a short period of time to dilute their blood sodium.
- Hyposmolar hyponatremia, also called hypotonic hyponatremia: Hyposmolality is a condition of having low levels of electrolytes (including sodium), proteins and nutrients. Hyponatremia can cause hyposmolality.
A note from Cleveland Clinic
Salt might not seem like it could be dangerous. But low levels of sodium in your bloodstream can be very dangerous. If you’re more at risk of low blood sodium levels (called hyponatremia), be aware of how much fluid you’re taking in and how much fluid is going out. Water leaves our bodies in the form of sweat, urine and vomit.
If you have any symptoms that worry you, like headaches or nausea, contact your healthcare provider, especially if you have chronic conditions like heart failure or kidney failure or endocrine system diseases. Balance in life is important, and so is balance in your bloodstream.
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