Hyponatremia is a condition that occurs as a result of abnormally low levels of sodium in the blood. Sodium is an electrolyte and it helps regulate the amount of water that is in and around the cells.

Various factors including underlying medical conditions or drinking too much water during endurance sports can cause for the sodium in the body to become diluted. Once this occurs, the levels of water in the body rise causing the cells to swell. The swelling can cause numerous health problems.

Treatment for hyponatremia focuses on resolving the underlying condition. Relative to the cause of hyponatremia, treatment may include drinking less water or IV fluids and medications.



Symptoms of hyponatremia may include:


  • Headache
  • Confusion
  • Nausea and vomiting
  • Fatigue and loss of energy
  • Restlessness and irritability
  • Muscle weakness, spasms or cramps
  • Seizures
  • Coma



Sodium is essential to the body. It regulates the body’s fluid balance; it helps to maintain normal blood pressure and supports the function of the nerves and muscles.

Potential causes and factors that can lead to hyponatremia include:


  • Certain medications: Diuretics, antidepressants and pain medications can cause frequent urination or abnormal perspiration.
  • Syndrome of inappropriate anti-diuretic hormone (SIADH): Syndrome in which there is an overproduction of anti-diuretic hormone, which causes the body to retain water instead of excreting it through urine.
  • Heart, kidney and liver problems: Congestive heart failure and kidney or liver diseases can cause fluid accumulation in the body, which dilutes the sodium and lowers its levels.
  • Chronic, severe vomiting or diarrhea: This results in loss of fluids and electrolytes.
  • Dehydration: Insufficient fluid intake leads to loss of fluids and electrolytes.
  • Drinking too much water: Too much water during endurance sports can dilute the sodium in the blood.
  • Hormonal changes: Conditions such as adrenal gland insufficiency can impair the adrenal glands’ ability to produce necessary hormones. Low levels of thyroid hormone can also cause low sodium levels.
  • Illegal drugs (Ecstasy): Ecstasy is an amphetamine, which increases the risk of severe and fatal cases of hyponatremia.


Risk factors

Risk factors for hyponatremia include:


  • Older age
  • Certain medications (diuretics, antidepressants, pain medications)
  • Conditions that decrease the body’s water excretion (kidney disease, SIADH, heart failure)
  • High water intake during intensive physical activities



In chronic hyponatremia, sodium levels drop gradually within a couple of days causing moderate symptoms and complications. On the other hand, in acute hyponatremia, sodium levels drop suddenly or rapidly causing serious complications such as rapid brain swelling, which can lead to coma or death.

Brain damage due to hyponatremia is more common in premenopausal women. This complication may be the result of the effect of women’s sex hormones on the body’s ability to balance sodium levels.



The following may help prevent hyponatremia:


  • Appropriate treatment for associated conditions (ex. adrenal gland insufficiency)
  • Precautions during intensive physical activities (drinking as much fluid as it is lost)
  • Sports beverages during intensive activities
  • Moderate water intake