What are the causes of hyponatremia (low sodium levels)?

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From the Guidelines

Low sodium levels, or hyponatremia, can be caused by various factors including certain medications, medical conditions like heart failure, kidney disease, liver cirrhosis, and adrenal gland disorders, as well as excessive fluid loss or retention. According to the most recent and highest quality study 1, the management of hyponatremia in patients with cirrhosis and ascites depends on the etiology, chronicity, severity, and urgency of the condition.

Causes of Hyponatremia

  • Certain medications like diuretics, antidepressants, and some pain medications
  • Medical conditions such as heart failure, kidney disease, liver cirrhosis, and adrenal gland disorders
  • Excessive sweating, vomiting, or diarrhea
  • Drinking too much water, particularly during endurance sports
  • Hormonal imbalances, especially involving antidiuretic hormone (ADH)
  • Certain dietary factors like extremely low-sodium diets

Treatment of Hyponatremia

  • For hypovolemic hyponatremia, treatment involves discontinuation of diuretics and/or laxatives and providing fluid resuscitation, typically with 5% IV albumin or crystalloid solution 1
  • For euvolemic hyponatremia, management should be based on the specific underlying cause
  • For hypervolemic hyponatremia, treatment includes fluid restriction, reduction or discontinuation of diuretics and laxatives, administration of hyperoncotic albumin, and/or vasopressin receptor antagonists (“vaptans”) 1

Important Considerations

  • Rapid correction of hyponatremia should be avoided to prevent osmotic demyelination syndrome (ODS) 1
  • The goal of treatment is to improve serum sodium concentration while minimizing the risk of complications 1
  • Vaptans, such as tolvaptan, can be effective in improving serum sodium concentration in patients with hypervolemic hyponatremia, but should be used with caution and close monitoring 1

From the Research

Reasons for Low Sodium

  • Low sodium levels, also known as hyponatremia, can be caused by various factors, including water retention, certain medications, and underlying medical conditions 2, 3.
  • Hyponatremia can be classified into three categories based on volume status: hypovolemic, euvolemic, and hypervolemic 3, 4.
  • Symptoms of hyponatremia can range from mild to severe and include weakness, nausea, seizures, and coma 2, 4.
  • Low sodium levels can also lead to increased risk of falls, fractures, and osteoporosis 2.

Treatment of Low Sodium

  • Treatment of hyponatremia depends on the underlying cause and severity of symptoms 2, 3.
  • Fluid restriction, isotonic saline, and diuresis are common treatment approaches for hyponatremia 3.
  • Hypertonic saline is used to treat severe symptomatic hyponatremia 2, 3.
  • Vasopressin receptor antagonists (VRAs) are a promising treatment for hyponatremia, particularly in patients with euvolemic and hypervolemic hyponatremia 5, 6.
  • VRAs work by increasing urinary dilution and leading to an increase in serum sodium concentration 5.

Complications of Low Sodium

  • Untreated hyponatremia can lead to increased morbidity and mortality, as well as longer hospital stays 2, 4.
  • Overly rapid correction of hyponatremia can cause osmotic demyelination, a rare but severe neurological condition 2.
  • Chronic hyponatremia can lead to cognitive impairment, gait disturbances, and increased risk of falls and fractures 2.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Hyponatraemia diagnosis and treatment clinical practice guidelines.

Nefrologia : publicacion oficial de la Sociedad Espanola Nefrologia, 2017

Research

When is it appropriate to use vasopressin receptor antagonists?

Journal of the American Society of Nephrology : JASN, 2008

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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