Critical Alerts

• Severe symptomatic hyponatremia is life-threatening: Cerebral edema, seizures
• Treat symptoms, not the number: Symptomatic needs emergent treatment
• 3% Hypertonic saline for severe symptoms: Raise Na 4-6 mEq/L acutely
• Limit correction to 8-10 mEq/L per 24 hours: Avoid osmotic demyelination syndrome (ODS)
• Chronic hyponatremia corrects slowly: Brain already adapted
• Acute hyponatremia (under 48 hours) can correct faster

Severity Classification

Emergency Treatments

Overcorrection Management

Overview

Hyponatremia is serum sodium under 135 mEq/L. Symptoms result from cerebral edema due to osmotic water shifts into brain cells. Severe or symptomatic hyponatremia requires emergent treatment with hypertonic saline. Correction must be carefully controlled to avoid osmotic demyelination syndrome (ODS). Workup identifies the underlying cause (volume status, tonicity, urine studies).

Classification

By Serum Osmolality:

By Volume Status (Hypotonic Hyponatremia):

Epidemiology

• Most common electrolyte disorder: Up to 30% of hospitalized patients
• Mortality higher with severe hyponatremia

Etiology

Common Causes:

Emergent Treatment Required

Step 1: Confirm True Hypotonic Hyponatremia

Serum Osmolality:

Step 2: Assess Volume Status

Step 3: Urine Studies

Additional Labs

Discharge Criteria (Mild/Moderate Asymptomatic)

• Sodium stable
• Underlying cause addressed
• Follow-up for recheck

Admission Criteria

• Symptomatic hyponatremia
• Na under 125 mEq/L
• Need for frequent monitoring
• Requiring hypertonic saline

ICU Admission

• Seizures, coma
• Requiring 3% saline boluses
• At high risk for ODS

Condition Explanation

• "Your sodium level is too low, which is causing problems with brain function."
• "We are carefully correcting this with special fluids."
• "Correcting too fast can cause a different problem, so we are monitoring closely."

Prevention

• Avoid excessive water intake
• Take medications as directed
• Follow fluid restrictions if prescribed

Performance Indicators

Documentation Requirements

• Sodium level and timeline
• Symptom severity
• Volume status
• Treatment given
• Correction rate
• Underlying cause

Diagnostic Pearls

• Confirm hypotonic (low osmolality): Rule out hypertonic and pseudo
• Correct Na for glucose: Add 1.6 mEq/L per 100 mg/dL glucose >100
• Urine Na >40 + Euvolemic = SIADH
• Urine Na under 20 + Hypovolemic = GI or renal losses
• Chronicity matters: Acute can correct faster

Treatment Pearls

• 3% Saline for severe symptoms: 100 mL bolus
• Goal: Raise Na 4-6 mEq/L acutely: Symptoms improve
• Limit correction to 8-10 mEq/L/24 hours: Prevent ODS
• D5W + DDAVP for overcorrection: Brings Na back down
• Fluid restriction for SIADH: First-line

Disposition Pearls

• Admit for Na under 125 or symptomatic
• ICU for seizures, coma, or hypertonic saline
• Monitor Na Q2h during treatment
• High-risk for ODS: Chronic, alcoholism, malnutrition, hypokalemia