At what level of hyponatremia (low sodium levels in the blood) should a patient be admitted?

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Last updated: May 12, 2025View editorial policy

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From the Guidelines

Patients with severe hyponatremia (serum sodium <120 mEq/L) or symptomatic hyponatremia should be admitted to the hospital, as they are at risk for life-threatening complications such as seizures, coma, and death 1. The decision to admit a patient with hyponatremia depends on several factors, including the severity of hyponatremia, the presence of symptoms, the rate of development, and the patient's overall clinical status.

  • Severe hyponatremia (serum sodium <120 mEq/L) is a medical emergency that requires immediate attention and hospitalization, as it can lead to life-threatening complications such as seizures, coma, and death 1.
  • Symptomatic hyponatremia, regardless of the serum sodium level, also requires hospitalization, as symptoms such as confusion, headache, and nausea can indicate a more severe underlying condition 1.
  • Patients with moderate hyponatremia (120-125 mEq/L) who have underlying conditions that may worsen or who are at risk for further sodium decline may also require hospitalization, as they are at risk for developing more severe hyponatremia and its associated complications 1.
  • Hospitalization allows for controlled correction of sodium levels, typically at a rate not exceeding 8-10 mEq/L in 24 hours to prevent osmotic demyelination syndrome, close monitoring of neurological status, and treatment of underlying causes 1.
  • Outpatient management may be appropriate for mild, chronic, asymptomatic hyponatremia (>130 mEq/L) in patients who can maintain adequate follow-up and have no concerning comorbidities 1.

From the Research

Admission Criteria for Hyponatremia

The decision to admit a patient with hyponatremia depends on the severity of symptoms and the underlying cause of the condition.

  • Severe symptomatic hyponatremia is associated with grave consequences, including cerebral edema, brain herniation, seizures, obtundation, coma, and respiratory arrest 2.
  • Patients with severe hyponatremia, defined as a serum sodium concentration less than 121 mmol/L, often require hospital admission 3.
  • The presence of neurologic symptoms, such as somnolence, disorientation, nausea, falls, and weakness, can indicate the need for admission 3.

Sodium Levels and Admission

  • A serum sodium concentration less than 135 mmol/L is generally considered hyponatremic 4.
  • Severe hyponatremia is typically defined as a serum sodium concentration less than 120 mmol/L 5.
  • Patients with severe hyponatremia, particularly those with symptoms, may require admission to the hospital for close monitoring and treatment 2, 6.

Treatment and Management

  • The treatment of hyponatremia depends on the underlying cause and severity of symptoms 4.
  • Hypertonic saline may be used to treat patients with hyponatremia associated with moderate or severe symptoms 6.
  • The correction rate of serum sodium is important, and a slow correction rate is associated with improved survival in patients with severe hyponatremia 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Treatment of severe symptomatic hyponatremia.

Physiological reports, 2019

Research

Hyponatraemia diagnosis and treatment clinical practice guidelines.

Nefrologia : publicacion oficial de la Sociedad Espanola Nefrologia, 2017

Research

Hypertonic Saline for Hyponatremia: Meeting Goals and Avoiding Harm.

American journal of kidney diseases : the official journal of the National Kidney Foundation, 2022

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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