When is 3% (normal saline) NS ordered for symptomatic severe hyponatremia?

When to Order 3% Normal Saline for Hyponatremia

3% hypertonic saline should be ordered immediately for severe symptomatic hyponatremia—defined by the presence of seizures, coma, altered mental status, or cardiorespiratory distress—regardless of the absolute sodium level. 1

Indications for 3% Hypertonic Saline

Severe Symptomatic Hyponatremia (Emergency Indication)

Administer 3% hypertonic saline for patients presenting with:

• Seizures 1, 2
• Coma or severely altered consciousness 1, 3
• Confusion, delirium, or obtundation 2, 3
• Cardiorespiratory distress 2

Initial treatment protocol:

• Give 100-150 mL bolus of 3% saline over 10 minutes 4, 5
• Can repeat up to three times at 10-minute intervals until symptoms improve 4
• Target correction: 4-6 mmol/L increase over the first 6 hours or until severe symptoms resolve 1, 2
• Critical safety limit: Do not exceed 8 mmol/L correction in 24 hours 1, 2, 3

Cerebral Salt Wasting (CSW) with Severe Symptoms

For neurosurgical patients with CSW and severe symptoms:

• Administer 3% hypertonic saline along with fludrocortisone 1
• CSW requires volume and sodium replacement, not fluid restriction 1
• More common than SIADH in neurosurgical patients, particularly those with subarachnoid hemorrhage 1

When NOT to Use 3% Hypertonic Saline

Asymptomatic or Mildly Symptomatic Hyponatremia

Do not use 3% saline for patients with:

• Mild symptoms only (nausea, headache, weakness) 1, 3
• Asymptomatic hyponatremia regardless of sodium level 1
• Instead: Implement fluid restriction to 1 L/day for SIADH 1
• Consider oral sodium chloride supplementation (100 mEq three times daily) if fluid restriction fails 1

Hypervolemic Hyponatremia Without Life-Threatening Symptoms

Avoid 3% saline in patients with:

• Cirrhosis with hypervolemic hyponatremia 1
• Heart failure with fluid overload 1
• Rationale: Hypertonic saline worsens edema and ascites 1
• Instead: Fluid restriction to 1-1.5 L/day and treat underlying condition 1

Discontinuation Criteria

Stop 3% hypertonic saline when:

• Severe symptoms resolve 6
• Initial correction goal of 6 mmol/L achieved over 6 hours 6
• Sodium reaches 131 mmol/L (except subarachnoid hemorrhage patients) 6

After discontinuation:

• Transition to fluid restriction (1 L/day) 6
• Monitor sodium every 4 hours instead of every 2 hours 6
• Limit additional correction to only 2 mmol/L in the following 18 hours 6

High-Risk Populations Requiring Cautious Correction

Patients at increased risk for osmotic demyelination syndrome require slower correction rates (4-6 mmol/L per day):

• Advanced liver disease 1, 7
• Chronic alcoholism 1
• Malnutrition 1
• Prior encephalopathy 1

Common Pitfalls to Avoid

• Using 3% saline for asymptomatic hyponatremia increases risk without benefit 1
• Exceeding 8 mmol/L correction in 24 hours can cause osmotic demyelination syndrome 1, 2
• Applying fluid restriction to cerebral salt wasting worsens outcomes—CSW requires volume replacement 1
• Inadequate monitoring during active correction leads to overcorrection complications 1
• Using 3% saline in hypervolemic states without severe symptoms exacerbates fluid overload 1