Low blood sodium
Hyponatremia; Dilutional hyponatremia; Euvolemic hyponatremia; Hypervolemic hyponatremia; Hypovolemic hyponatremiaLow blood sodium is a condition in which the sodium level in the blood is lower than normal. The medical name of this condition is hyponatremia.
Causes
Sodium is found mostly in the body fluids outside the cells. Sodium is an electrolyte (mineral). It is very important for maintaining blood pressure. Sodium is also needed for nerves, muscles, and other body tissues to work properly.
Electrolyte
Electrolytes are minerals in your blood and other body fluids that carry an electric charge. Electrolytes affect how your body functions in many ways...
Read Article Now Book Mark ArticleWhen the amount of sodium in fluids outside cells drops below normal, water moves into the cells. This causes the cells to swell with too much water. Brain cells are especially sensitive to swelling, and this causes many of the symptoms of low blood sodium.
With hyponatremia, the imbalance of water to sodium is caused by one of three conditions:
The imbalance of water to sodium
Every part of your body needs water to function. When you are healthy, your body is able to balance the amount of water that enters or leaves your b...
Read Article Now Book Mark Article- Euvolemic hyponatremia -- total body water increases, but the body's sodium content stays the same
- Hypervolemic hyponatremia -- both sodium and water content in the body increase, but the water gain is greater
- Hypovolemic hyponatremia -- water and sodium are both lost from the body, but the sodium loss is greater
Low blood sodium can be caused by:
- Burns that affect a large area of the body
- Diarrhea
- Diuretic medicines (water pills), which increase urine output and loss of sodium through the urine
- Heart failure
Heart failure
Heart failure is a condition in which the heart is no longer able to pump oxygen-rich blood to the rest of the body efficiently. This causes symptom...
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- Cirrhosis (advanced liver disease)
Cirrhosis
Cirrhosis is scarring of the liver and poor liver function. It is the last stage of chronic liver disease.
Read Article Now Book Mark Article - Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Syndrome of inappropriate antidiuretic ...
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a condition in which the body makes too much antidiuretic hormone (ADH). ADH is ...
Read Article Now Book Mark Article - Sweating
- Vomiting
Symptoms
Common symptoms include:
- Confusion, irritability, restlessness
Confusion
Confusion is the inability to think as clearly or quickly as you normally do. You may feel disoriented and have difficulty paying attention, remembe...
Read Article Now Book Mark Article - Convulsions
Convulsions
A seizure is the physical changes in behavior that occurs during an episode of specific types of abnormal electrical activity in the brain. The term ...
Read Article Now Book Mark Article - Fatigue
Fatigue
Fatigue is a feeling of weariness, tiredness, or lack of energy.
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- Loss of appetite
Loss of appetite
A decreased appetite is when your desire to eat is reduced. The medical term for a loss of appetite is anorexia.
Read Article Now Book Mark Article - Muscle weakness, spasms, or cramps
Muscle weakness
Muscle cramps are when a muscle gets tight (contracts) without you trying to tighten it, and it does not relax. Cramps may involve all or part of on...
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Exams and Tests
Your health care provider will perform a complete physical examination and ask about your symptoms. Blood and urine tests will be done.
Lab tests that can confirm and help diagnose low sodium include:
- Comprehensive metabolic panel (includes blood sodium, normal range is 135 to 145 mEq/L, or 135 to 145 mmol/L)
Comprehensive metabolic panel
A comprehensive metabolic panel is a group of blood tests. They provide an overall picture of your body's chemical balance and metabolism. Metaboli...
Read Article Now Book Mark Article - Blood osmolality
Blood osmolality
Osmolality blood test is a test that measures the concentration of all chemical particles found in the fluid part of blood. Osmolality in the urine c...
Read Article Now Book Mark Article - Urine osmolality
Urine osmolality
The osmolality urine test measures the concentration of chemicals in urine. Osmolality in the blood can be measured using a blood test.
Read Article Now Book Mark Article - Urine sodium (normal level is 20 mEq/L in a random urine sample, and 40 to 220 mEq per day for a 24-hour urine test)
Urine sodium
The sodium urine test measures the amount of sodium the urine. Sodium can also be measured in a blood sample.
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Treatment
The cause of low blood sodium must be diagnosed and treated. If cancer is the cause of the condition, then radiation, chemotherapy, or surgery to remove the tumor may correct the sodium imbalance.
Chemotherapy
The term chemotherapy is used to describe cancer-killing drugs. Chemotherapy may be used to:Cure the cancerShrink the cancerPrevent the cancer from ...
Read Article Now Book Mark ArticleOther treatments depend on the specific type of hyponatremia.
Treatments may include:
- Fluids through a vein (IV)
- Medicines to relieve symptoms
- Limiting water intake
Outlook (Prognosis)
Outcome depends on the condition that is causing the problem. Hyponatremia that occurs in less than 48 hours (acute hyponatremia), is more dangerous than hyponatremia that develops slowly over time. When blood sodium level falls slowly over days or weeks (chronic hyponatremia), the brain cells have time to adjust and swelling may be minimal.
Possible Complications
In severe cases, low blood sodium can lead to:
- Decreased consciousness, hallucinations or coma
- Brain herniation
Brain herniation
Brain herniation is the shifting of the brain tissue from one space in the skull to another through various folds and openings.
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When to Contact a Medical Professional
When your body's sodium level drops too much, it can be a life-threatening emergency. Call your provider right away if you have symptoms of this condition.
Prevention
Treating the condition that is causing hyponatremia can help.
If you play sports or do other vigorous activity, drink fluids such as sports drinks that contain electrolytes to keep your body's sodium level in a healthy range.
Electrolytes
Electrolytes are minerals in your blood and other body fluids that carry an electric charge. Electrolytes affect how your body functions in many ways...
Read Article Now Book Mark ArticleReferences
Dell KM. Fluid, electrolytes, and acid-base homeostasis. In: Martin RJ, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 92.
Pasco J. Electrolyte disturbances. In: Cameron P, Little M, Mitra B, Deasy C, eds. Textbook of Adult Emergency Medicine. 5th ed. Philadelphia, PA: Elsevier; 2020:chap 12.2
Verbalis JG. Disorders of water balance. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 15.
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Review Date: 6/12/2023
Reviewed By: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.