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

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From the Guidelines

Hyponatremia is primarily caused by excessive water intake, increased antidiuretic hormone (ADH) secretion, certain medications, and medical conditions such as heart failure, cirrhosis, kidney disease, and adrenal insufficiency, as supported by the most recent and highest quality study 1.

Causes of Hyponatremia

The causes of hyponatremia can be categorized into several groups, including:

  • Excessive water intake that dilutes sodium concentration
  • Increased antidiuretic hormone (ADH) secretion that prevents water excretion
  • Certain medications like thiazide diuretics, SSRIs, carbamazepine, and NSAIDs
  • Medical conditions such as heart failure, cirrhosis, kidney disease, and adrenal insufficiency
  • Other causes include excessive sweating without adequate sodium replacement, vomiting or diarrhea, certain endocrine disorders like hypothyroidism and SIADH, and nutritional deficiencies in severe cases

Treatment of Hyponatremia

Treatment of hyponatremia depends on the underlying cause and may include:

  • Fluid restriction
  • Sodium supplementation
  • Medication adjustments
  • Addressing the primary condition causing the electrolyte imbalance According to the most recent guidelines 1, treatment of hyponatremia in cirrhotic ascites depends on etiology, chronicity, severity, and urgency, and may involve fluid restriction, reduction or discontinuation of diuretics and laxatives, administration of hyperoncotic albumin, and/or vasopressin receptor antagonists.

Key Considerations

  • The severity of symptoms correlates with how quickly sodium levels drop, with rapid decreases being more dangerous than gradual ones
  • Treatment should be started in the hospital with close clinical monitoring and assessment of serum sodium levels to avoid increases of serum sodium of more than 8-10 mmol/L/day
  • Vaptans, such as tolvaptan, have been shown to be effective in improving serum sodium concentration in patients with cirrhosis and hyponatremia, but should be used with caution and under close monitoring 1

From the FDA Drug Label

resulting from a variety of underlying causes (heart failure, liver cirrhosis, syndrome of inappropriate antidiuretic hormone [SIADH] and others) The causes of hyponatremia (low sodium levels) include:

  • Heart failure
  • Liver cirrhosis
  • Syndrome of inappropriate antidiuretic hormone (SIADH)
  • Other underlying causes 2

From the Research

Causes of Hyponatremia

The causes of hyponatremia can be categorized based on the patient's fluid volume status:

  • Hypovolemic hyponatremia: caused by diarrhea, vomiting, or other gastrointestinal fluid losses 3
  • Euvolemic hyponatremia: caused by the syndrome of inappropriate antidiuretic hormone secretion (SIADH), also known as Schwartz-Bartter syndrome 3
  • Hypervolemic hyponatremia: caused by cardiac failure and liver cirrhosis 3, 4, 5

Common Causes of Hyponatremia

Some common causes of hyponatremia include:

  • Certain medications 6
  • Excessive alcohol consumption 6
  • Very low-salt diets 6
  • Excessive free water intake during exercise 6
  • Increased activity of arginine vasopressin (AVP) in patients with congestive heart failure (CHF) 5
  • Diuretic therapy used in the management of symptoms of CHF 5

Underlying Conditions Associated with Hyponatremia

Hyponatremia can be associated with various underlying conditions, including:

  • Heart failure 7, 6, 4, 5
  • Liver cirrhosis 7, 6, 4
  • Osteoporosis 7
  • Syndrome of inappropriate antidiuretic hormone secretion (SIADH) 7, 3

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

[Hyponatremia].

Medizinische Klinik, Intensivmedizin und Notfallmedizin, 2013

Research

Hyponatremia in congestive heart failure.

The American journal of cardiology, 2005

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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