Hyponatremia: What Is Another Name for Low Sodium?

December 15, 2025 •

3 min read

Affecting up to 20% of hospitalized patients, low sodium, medically known as hyponatremia, is the most common electrolyte disorder. Understanding this condition is crucial for recognizing symptoms and seeking timely treatment.

Quick Summary

Hyponatremia is the medical term for low sodium levels. This condition can result from excess fluid, medication side effects, or underlying health issues, leading to serious complications if untreated.

Key Points

Hyponatremia: The medical term for low sodium is hyponatremia, defined as a serum sodium level below 135 mEq/L.
Key Causes: Common triggers include fluid retention, excessive sweating, certain medications, and hormonal imbalances.
Varied Symptoms: Symptoms range from mild, like headaches and fatigue, to severe, including confusion, seizures, and coma.
Personalized Treatment: Treatment depends on the underlying cause and severity, and may involve fluid restriction, medication adjustments, or intravenous fluids.
Prevention: Balancing water intake with electrolytes is important, especially during intense exercise.
Serious Complications: Untreated hyponatremia can lead to severe neurological issues.

The Scientific Name for Low Sodium: Hyponatremia

When healthcare professionals discuss low blood sodium, they refer to the medical condition called hyponatremia. This term combines Greek and Latin roots: 'hypo' for low, 'natrium' for sodium, and 'emia' indicating a blood condition. It is defined by a serum sodium concentration below 135 milliequivalents per liter (mEq/L), with the normal range typically between 135 and 145 mEq/L. Maintaining this balance is vital for functions like nerve impulses, muscle contractions, and fluid regulation. A disruption can cause water to enter and swell the body's cells, which can be particularly dangerous for brain cells.

The Diverse Causes of Hyponatremia

Hyponatremia is often a symptom of another issue, with causes categorized based on the body's fluid volume: hypovolemic (low volume), euvolemic (normal volume), and hypervolemic (high volume).

Common causes include excessive fluid retention (e.g., from heart failure, kidney disease, or SIADH), excessive loss of sodium and fluid (e.g., severe vomiting, diarrhea, intense sweating), and certain medications (e.g., diuretics, some antidepressants). Age is also a risk factor. For a more detailed breakdown of causes, refer to {Link: Verywell Health https://www.verywellhealth.com/hyponatremia-low-sodium-2488674}.

Recognizing the Symptoms of Low Sodium

The symptoms of hyponatremia vary with severity and the speed of sodium level drop. Mild cases might have minimal symptoms, while severe, acute hyponatremia can be critical.

Common symptoms include:

Nausea and vomiting
Headache
Fatigue
Restlessness and irritability
Muscle issues like weakness or cramps
Confusion or other mental changes

Severe symptoms needing immediate medical care:

Seizures
Loss of consciousness or coma

Diagnosis and Treatment of Hyponatremia

Diagnosis starts with a blood test to check serum sodium levels. Further tests, like urine tests and a physical exam, help identify the underlying cause and fluid status. Treatment is tailored to the individual and aims to correct the sodium imbalance and address the cause.

Treatment options may include:

Fluid Restriction: Often used for cases involving excess water.
Intravenous (IV) Fluids: Administered in severe, acute cases to slowly and safely raise sodium levels under medical supervision.
Medication Adjustment: If a medication is the cause, adjustments may be made.
Medications: Specific drugs may be used to manage hyponatremia in certain situations.

Comparison of Hyponatremia Types


Feature	Hypovolemic Hyponatremia	Hypervolemic Hyponatremia
Cause	Loss of both sodium and water, with more sodium lost.	Increase in both sodium and water, with more water gained.
Associated Conditions	Prolonged vomiting, severe diarrhea, diuretic use, Addison's disease.	Congestive heart failure, liver cirrhosis, nephrotic syndrome.
Fluid Status	Clinically dehydrated (low total body water).	Clinically edematous (excess total body water).
Urine Sodium	Typically low (<20 mEq/L) as kidneys try to conserve sodium.	Variable, depending on the underlying condition.
Treatment Focus	Replenishing both fluid and sodium with IV fluids.	Treating the underlying condition and restricting fluids.

Preventing Hyponatremia

Preventing hyponatremia can be challenging when caused by chronic illness. However, managing fluid and electrolyte intake, especially during endurance activities, can reduce the risk of exercise-associated hyponatremia. General health management is also important, including working with your doctor on chronic conditions and reviewing medications.

Conclusion: Timely Identification is Key

Hyponatremia, or low sodium, is a common and potentially serious electrolyte issue with various causes. Recognizing symptoms and risk factors is crucial for prompt diagnosis and appropriate treatment. This helps prevent severe complications like brain swelling or seizures and improves health outcomes. Managing your health and discussing any concerns with your doctor is the best approach to addressing and preventing hyponatremia.

For more information, the National Kidney Foundation offers resources.

Frequently Asked Questions

Low blood sodium, or hyponatremia, means the balance of water and sodium in your body is disrupted. This can cause cells to swell, affecting many bodily functions, especially in the brain, and can lead to serious neurological symptoms in severe cases.

Symptoms can range from mild issues like nausea, headache, and fatigue to more severe problems including confusion, muscle cramps, and seizures. The severity depends on how low the sodium levels are and how quickly they drop.

Hyponatremia is diagnosed with a simple blood test that measures your serum sodium level. Further evaluation, including urine tests, can help a doctor determine the underlying cause.

Common causes include excessive fluid intake, especially during intense exercise; medication side effects from diuretics or antidepressants; vomiting and diarrhea; and underlying conditions like heart, kidney, or liver disease.

While not all cases are preventable, you can reduce risk by managing underlying medical conditions, drinking fluids with electrolytes during intense exercise, and using thirst as a guide for water intake. Always discuss medication side effects with your doctor.

Risk factors include age (older adults), certain medications (e.g., diuretics, SSRIs), underlying conditions (heart, liver, or kidney disease), intense physical activity, and excessive water consumption.

Treatment varies based on the cause and severity. Options include fluid restriction, medication adjustments, or in severe cases, intravenous fluids administered in a hospital setting.

Hyponatremia is low blood sodium, while hypokalemia is low blood potassium. Both are electrolyte imbalances, but they affect different electrolytes, though diuretics can cause both to occur together.