by EBSCO Medical Review Board
(Dilutional Hyponatremia; Euvolemic Hyponatremia; Hypervolemic Hyponatremia; Hypovolemic Hyponatremia)


Hyponatremia is a low level of sodium in the blood. It can be deadly if it is not treated.


This problem happens when there is too much water for the amount of sodium in the body.

This problem may be caused by:

  • Drinking too many fluids
  • Loss of sodium in fluids due to sweating, vomiting, or diarrhea (less common)
Normal Anatomy of the Kidney
Kidney failure stones
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Risk Factors

This problem is more common in older adults. Other things that may raise the risk are:

  • Endurance exercise, such as running
  • Taking certain medicines, such as diuretics or anti-psychotics
  • Recent surgery, especially prostate or uterine surgery
  • Certain health problems, such as:
    • Kidney failure
    • Diabetes
    • Stroke
    • Cancer
    • Chronic obstructive pulmonary disorder
    • Mental health problems


Problems may be:

  • Headache
  • Nausea
  • Loss of appetite
  • Irritability
  • Restlessness
  • Sluggishness
  • Confusion
  • Muscle twitching
  • Hallucinations
  • Seizures


You will be asked about your symptoms and health history. A physical exam will be done.

Blood and urine tests will be done to check sodium levels.


Treatment depends on what is causing the problem and how severe symptoms are. The goal is to slowly raise sodium levels. Options are:

  • Limiting fluids
  • Raising sodium levels using an IV solution or pills
  • Giving medicine to help balance fluid without losing more sodium
  • Changing or stopping any medicines that may be causing low sodium levels


The risk of this problem may be lowered by drinking only as much fluid as is needed to meet thirst. Long or intense activity may need drinks with electrolytes.


American Society for Nutrition 

National Institute of Diabetes and Digestive and Kidney Diseases 


The College of Family Physicians of Canada 

Health Canada 


Hyponatremia. EBSCO DynaMed website. Available at: Accessed August 19, 2021.

Hyponatremia. Merck Manual Professional Version website. Available at: Accessed August 19, 2021.

Revision Information

  • Reviewer: EBSCO Medical Review Board James Cornell, MD
  • Review Date: 07/2021
  • Update Date: 08/19/2021