What is hypervolemic hyponatremia?

Hyponatremia is a term used to describe a low blood sodium level. Sodium is an electrolyte that works in the body to regulate the amount of water in and surrounding the cells. A normal blood sodium level is 135-145 milliEquivalents/liter. There are many different causes for hyponatremia. The electrolyte imbalance may occur on its own or as a result of another condition.
The term hypervolemic hyponatremia refers to a decrease in the body’s blood sodium level with an increase in total body water. When the sodium in one’s body is low, the body’s water level rises and causes the cells to swell which can result in serious health problems. Some potential causes for hypervolemic hyponatremia include congestive heart failure, renal disease, and liver cirrhosis. In people with hypervolemic hyponatremia there is a decrease in free water excretion from the body, causing water retention even in the presence of low sodium. This creates a significant imbalance which then causes increased extracellular volume and hyponatremia. 
Hyponatremia can be classified into the following categories. Symptoms and complications due to hyponatremia may vary in severity depending on the category one falls into.
  • Mild: A sodium level ranging from 130-134 mEq/L
  • Moderate: A sodium level ranging from 125-129 mEq/L
  • Profound: A sodium level that is less than 125 mEq/L
Risk factors
  • Age: Older adults are at an increased risk for hyponatremia
  • Renal disease/kidney injury
  • Congestive heart failure
  • Liver cirrhosis
  • Syndrome of inappropriate antidiuretic hormone (SIADH)
  • Certain drugs can increase one’s risk for hyponatremia such as thiazide diuretics, certain antidepressants, certain pain medications, and ecstasy.
  • Drinking too much water while doing intensive physical activities such as running marathons. 
When diagnosing hypervolemic hyponatremia, your doctor will likely do a complete medical history and physical exam, paying close attention to any signs and symptoms you may be experiencing. 
Some tests that may be done to diagnose hypervolemic hyponatremia include:
  • Serum osmolality is a blood test done to look at the amount of sodium in one’s blood. This test also looks at the levels of other substances in one’s blood such as chloride, glucose, proteins, and bicarbonate. 
  • Urine osmolality looks at a sample of one’s urine to see how concentrated or dilute it is. 
  • Urinary sodium concentration is done to differentiate between hyponatremia caused by hypovolemia (low water level in the body) or hyponatremia caused by syndrome of inappropriate antidiuretic hormone (SIADH). 
Treatment for hypervolemic hyponatremia is aimed at treating whatever is causing the imbalance. If one’s hyponatremia is chronic due to diet or drinking too much water, cutting back on water intake may be effective in correcting the problem. 
Treatment for acute episodes of hypervolemic hyponatremia include:
  • Medications to treat any signs, symptoms, and complications
  • Loop diuretics
  • Fluid and sodium restriction 
  • Treat the underlying condition/cause
  • The most common causes of hypervolemic hyponatremia are renal disorders, liver cirrhosis, and congestive heart failure. 
  • Hyponatremia is the most common electrolyte abnormality in hospitalized patients.
  • Hyponatremia among hospitalized patients is associated with increased morbidity and mortality. 
about hypervolemia hyponatremia

  • "Hyponatremia." Mayo Clinic. Mayo Foundation for Medical Education and Research, 28 May. 2014. Web. 13 Oct. 2017.
  • “Pathophysiology of Hypervolemic Hyponatremia.” Cumberland Pharmaceuticals Inc, n.d. Web. 13 Oct. 2017. 
  • “Hyponatremia.” WebMD. Medscape, 26 Jul. 2016. Web. 13 Oct. 2017. 
  • “Management of Hyponatremia.” American Academy of Family Physicians. American Family Physician, 15 May. 2004. Web. 13 Oct. 2017. 
  • “Hypervolemic hyponatremia: Clinical significance and management.” American Association for the Study of Liver Diseases. Clinical Liver Disease A Multimedia Review Journal, 21 Jun. 2013. Web. 13 Oct. 2017. 
  • “Hyponatremia (Low Blood Sodium).” Medicine.net, n.d. Web. 13 Oct. 2017. 
  • “Serum Osmolality.” WebMD, n.d. Web. 13 Oct. 2017.
  • “Prevalence of hyponatremia and association with mortality: Results from NHANES.” National Center for Biotechnology Information. U.S. National Library of Medicine, Dec. 2013. Web. 13 Oct. 2017. 



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