What causes hypernatremia?

Hypernatremia is caused by dehydration, excessive sodium intake, kidney disease, or endocrine disorders such as diabetes insipidus. Dehydration from inadequate fluid intake, excessive sweating, vomiting, or diarrhea concentrates sodium in your blood. Kidney disorders prevent proper sodium excretion, while diabetes insipidus disrupts the hormone vasopressin, causing excessive water loss through urination. Certain medications like diuretics and conditions affecting your thirst mechanism can also elevate blood sodium levels.

What is the best test for hypernatremia?

The Electrolyte Panel is the most important test for hypernatremia because it directly measures your blood sodium concentration along with potassium, chloride, and bicarbonate levels. This test provides immediate confirmation of elevated sodium levels above 145 mEq/L and helps identify electrolyte imbalances. For a more comprehensive evaluation, the Comprehensive Metabolic Profile includes sodium measurement plus kidney function markers like creatinine and eGFR, which reveal whether kidney dysfunction is contributing to your high sodium levels. The Kidney Function Profile is essential if kidney disease is suspected as the underlying cause.

When should I get tested for hypernatremia?

You should get tested if you experience symptoms like excessive thirst, confusion, irritability, muscle twitching, or seizures. Testing is important if you have been severely dehydrated from illness, heat exposure, or inadequate fluid intake. People with diabetes insipidus, chronic kidney disease, or those taking diuretics should monitor their sodium levels regularly. If you notice persistent dry mouth, decreased urination, or sudden changes in mental status, immediate testing is warranted.

What are the symptoms of hypernatremia?

Symptoms of hypernatremia include intense thirst, dry mouth, restlessness, and confusion. You might experience muscle weakness, twitching, or spasms as your sodium levels rise. Severe cases can cause lethargy, seizures, loss of consciousness, and coma. Older adults may show subtle signs like increased irritability or altered mental status. The severity of symptoms depends on how quickly sodium levels rise and how high they climb.

Who is at risk for hypernatremia?

Older adults are at highest risk due to decreased thirst sensation and reduced kidney function. People with diabetes insipidus, kidney disease, or Cushing syndrome face increased risk. Infants and young children are vulnerable because they cannot communicate thirst effectively. Athletes and outdoor workers who lose excessive fluid through sweat without adequate replacement are at risk. Hospitalized patients, especially those receiving intravenous sodium solutions or tube feedings, require careful monitoring.

What happens if hypernatremia is left untreated?

Untreated hypernatremia causes brain cells to shrink as water moves out to balance sodium concentration, leading to brain damage. You can develop seizures, permanent neurological damage, or fall into a coma. Severe hypernatremia increases risk of brain hemorrhage from torn blood vessels as the brain shrinks. Chronic high sodium levels strain your cardiovascular system and worsen kidney function. Without treatment, severe hypernatremia can be fatal, particularly in vulnerable populations like infants and elderly individuals.

Can hypernatremia be diagnosed with a blood test?

Yes, hypernatremia is definitively diagnosed with a simple blood test that measures serum sodium concentration. The Electrolyte Panel directly identifies sodium levels above the normal range of 135-145 mEq/L. Additional blood tests like the Comprehensive Metabolic Profile evaluate kidney function and other metabolites to determine the underlying cause. Your doctor may also order urine tests to assess how your kidneys are handling sodium and water, helping distinguish between different types of hypernatremia.

How is hypernatremia treated?

Treatment involves gradually replacing lost fluids to lower sodium levels safely. You may receive oral fluids if you can drink, or intravenous fluids if dehydration is severe. The correction must happen slowly to prevent brain swelling from rapid sodium changes. If diabetes insipidus is the cause, medications like desmopressin replace the missing hormone. Treating underlying conditions such as kidney disease and adjusting medications that contribute to sodium elevation are essential for long-term management.

How can I prevent hypernatremia?

Prevent hypernatremia by drinking adequate fluids throughout the day, especially during hot weather or exercise. Monitor your fluid intake if you have conditions affecting thirst or kidney function. Limit high-sodium foods and avoid excessive salt supplementation. If you take diuretics or other medications affecting fluid balance, work closely with your doctor to monitor electrolyte levels. Elderly individuals and those with chronic illnesses should establish regular hydration routines and watch for early signs of dehydration.

What can I do at home for hypernatremia?

At home, focus on increasing your fluid intake with water or electrolyte-balanced drinks, avoiding excessive plain water which can cause other imbalances. Reduce dietary sodium by limiting processed foods, canned soups, and salty snacks. Eat water-rich foods like cucumbers, watermelon, and celery. Keep a water bottle nearby as a reminder to drink regularly. However, do not attempt to self-treat severe hypernatremia, as rapid correction can be dangerous. Seek medical attention if you experience confusion, severe thirst, or neurological symptoms.

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Hypernatremia Blood Test | Private MD Labs

Hypernatremia (High Sodium) Blood Test

What is Hypernatremia?

Hypernatremia is a condition where blood sodium levels exceed 145 mEq/L, indicating abnormally high sodium concentration. It is caused by dehydration, excessive sodium intake, kidney disease, or endocrine disorders such as diabetes insipidus. The Electrolyte Panel is the most important test for diagnosis because it directly measures sodium levels and other essential electrolytes.

Written by Private MD Labs Medical Team

Last updated: December 30, 2025

Getting your blood test with us is easy, private & backed by the power of science.

Long story short:

In the test options, use the filters or search box to narrow your choices and find the test you want.
If you need a hand navigating through options, text our super friendly support team at 754-799-7833, and we'll provide tailored suggestions to help you find the ideal test.
Once your order is placed, we’ll create your doctor’s lab order remotely, without any need for you to make a trip to a doctor in person or to talk to the doctor. Expect to receive your doctor’s lab order right in your inbox. It will also be in your patient portal if you need to find it later. We’ll also include instructions regarding fasting and other requirements for your test. Your patient portal will be auto-created hassle-free during checkout.
If this is your first time ordering, you'll be prompted to create a password for instant login access to your patient portal. It's a quick way to conveniently access your orders and results whenever you want.
When you’re ready, visit one of our 4,000 locations. Just bring your ID – no printing or faxing of your lab order is needed, as your order and details will already be in the lab system.
Note that most lab locations don’t accept walk-ins, so it’s best to book an appointment in advance. Don’t worry – we’ll provide detailed instructions along the way.
You’ll get your results via email & SMS and dive into understanding your body better. Yup, that easy!

754-799-7833

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