Sodium is an essential electrolyte that helps maintain the balance of water in and around your cells. It’s important for proper muscle and nerve function. It also helps maintain stable blood pressure levels.
Insufficient sodium in your blood is known as hyponatremia. It occurs when water and sodium are out of balance. In other words, there’s either too much water or not enough sodium in your blood.
Normally, your sodium level should be between 135 and 145 milliequivalents per liter. Hyponatremia occurs when your sodium level goes below 135 mEq/L.
Symptoms of low blood sodium can vary from person to person. If your sodium levels fall gradually, you may not experience any symptoms at first, but they will eventually manifest. If they drop very quickly, your symptoms may be more obvious and severe.
Common symptoms of hyponatremia include:
Severe symptoms of hyponatremia
Losing sodium quickly is a medical emergency. It can cause:
- overactive reflexes
- loss of consciousness
- and in the most severe cases, death
If you or someone you know seems to be losing consciousness or is having a seizure, call 911 immediately.
Many factors can cause hyponatremia. Your sodium levels may get too low if your body loses too much water and electrolytes. Hyponatremia may also be a symptom of certain medical conditions.
Causes of hyponatremia include:
- severe vomiting or diarrhea
- taking certain medications, including antidepressants and pain medications
- taking diuretics (water pills)
- drinking too much water during exercise (this is very rare)
- kidney disease or kidney failure
- liver disease
- heart problems, including congestive heart failure
- adrenal gland disorders, such as Addison’s disease, which affects your adrenal gland’s ability to regulate the balance of sodium, potassium, and water in your body
- hypothyroidism (underactive thyroid)
- syndrome of inappropriate antidiuretic hormone (SIADH), which makes your body retain water
- diabetes insipidus, a rare condition in which the body doesn’t make antidiuretic hormone
- Cushing’s syndrome, which causes high cortisol levels (this is rare)
Certain factors increase your risk of hyponatremia, including:
- older age
- diuretic use
- antidepressant use
- being a high-performance athlete (i.e., a marathon runner)
- living in a warmer climate
- eating a low-sodium diet
- having heart failure, kidney disease, syndrome of inappropriate antidiuretic hormone (SIADH), or other conditions
If you’re at risk for low sodium, you may need to be more careful about your intake of electrolytes and water. Make sure to talk to your doctor about your risk factors and if there are any steps you can take to lessen your risk.
If hyponatremia is not treated, it can lead to serious complications, including:
- brain swelling
- brain injury
- osteoporosis and bone fractures
If you are at a higher risk for hyponatremia due to preexisting conditions, it’s important to take any new symptom seriously and talk to a doctor as quickly as possible.
A blood test can help your doctor check for low sodium levels. Even if you don’t have symptoms of low blood sodium, your doctor may order a basic metabolic panel. This tests the amounts of electrolytes and minerals in your blood.
A basic metabolic panel is often part of a routine physical. It may identify low blood sodium in someone without any symptoms.
If your levels are abnormal, your doctor will order a urine test to check the amount of sodium in your urine. The results of this test will help your doctor determine the cause of your low blood sodium:
- If your blood sodium levels are low but your urine sodium levels are high, your body is losing too much sodium.
- Low sodium levels in both your blood and your urine mean your body isn’t taking in enough sodium. There may also be too much water in your body.
If your doctor is still unsure of a diagnosis, they may order a few other tests to check for hyponatremia,
- liver function tests
- a chest X-ray or computed tomography (CT) scan of your chest
- CT scan of your head
Treatment for low blood sodium varies depending on the cause, how severe the symptoms are, and how low your blood sodium levels are. It may include:
- cutting back on fluid intake
- adjusting the dosage of diuretics
- taking medications for symptoms such as headaches, nausea, and seizures
- treating underlying conditions
- stopping or changing a medication for a chronic condition that may be negatively affecting blood sodium
- an intravenous (IV) sodium solution
Keeping your water and electrolyte levels as balanced as possible can help prevent low blood sodium.
If you’re an athlete, it’s important to drink the right amount of water during exercise.
You may also want to consider drinking rehydration beverages. These drinks contain electrolytes, and help replenish sodium lost through sweating. These drinks are also helpful if you lose a lot of fluids through vomiting or diarrhea.
Staying hydrated throughout the day can help manage any wild swings in blood sodium. When you’re adequately hydrated, your urine will be pale yellow or clear, and you won’t feel thirsty.
It’s important to increase your fluid intake if:
- the weather is warm
- you’re at a high altitude
- you’re pregnant or breastfeeding
- you’re vomiting
- you have diarrhea
- you have a fever
Don’t forget that it’s possible to drink too much water too quickly. This is another reason to maintain good hydration throughout the day.
Hypernatremia is a condition that is closely related to hyponatremia.
What is hypernatremia?
While hyponatremia involves low levels of sodium in the blood, hypernatremia occurs when there is too much sodium.
When a person doesn’t get enough water, either because of limited access to water or an impaired thirst mechanism, they can develop hypernatremia. It’s caused less commonly by diabetes insipidus.
Hypernatremia occurs when your serum sodium level
Hypernatremia can cause:
Hyponatremia is diagnosed when there is too little sodium in your blood. It can be caused by a variety of factors, from conditions like Addison’s disease or Cushing’s syndrome, to excessive vomiting or diarrhea.
Hyponatremia can be mild, and cause no symptoms, or it can be very severe and life threatening.
Typically, if hyponatremia is caught in the mild stage and treated, or treated swiftly in the severe stage, it can be reversed.