How to treat hypernatremia with a sodium level of 165 mmol/L?

Management of Hypernatremia with Sodium Level of 165 mmol/L

Hypernatremia with a sodium level of 165 mmol/L should be treated with hypotonic fluid administration, with a correction rate not exceeding 8-10 mmol/L per day to prevent neurological complications.

Assessment and Classification

Before initiating treatment, determine:

• Duration of hypernatremia (acute vs chronic)
  • Acute: <48 hours
  • Chronic: >48 hours (most common in clinical settings)
• Volume status (hypovolemic, euvolemic, or hypervolemic)
• Presence of neurological symptoms
• Underlying cause (water deficit, sodium excess, or both)

Treatment Algorithm

Step 1: Calculate Water Deficit

Water deficit (L) = Total body water × [(Current Na⁺/140) - 1]

• Total body water = 0.5-0.6 × body weight (kg) for adults

Step 2: Choose Appropriate Fluid

• Hypovolemic hypernatremia: Start with isotonic (0.9%) saline to restore hemodynamic stability, then switch to hypotonic fluids (0.45% saline or 5% dextrose)
• Euvolemic hypernatremia: Use hypotonic fluids (0.45% saline or 5% dextrose in water)
• Hypervolemic hypernatremia: Use hypotonic fluids plus loop diuretics to promote free water retention and sodium excretion

Step 3: Determine Correction Rate

• For chronic hypernatremia (>48 hours duration, which is most common):
  • Maximum correction rate: 8-10 mmol/L/day 1
  • Target initial correction: 4-6 mmol/L in first 24 hours
• For acute hypernatremia (<24 hours):
  • Can correct more rapidly, but still monitor closely
  • Consider hemodialysis for very severe cases 1

Step 4: Monitor Closely

• Check serum sodium every 2-4 hours initially, then every 4-6 hours
• Adjust fluid rate based on sodium measurements
• Monitor for neurological changes
• Track fluid input/output and daily weights

Special Considerations

Severe Neurological Symptoms

If severe neurological symptoms are present (seizures, coma):

• More aggressive initial correction may be warranted
• Still aim to not exceed 10 mmol/L/day total correction

Prevention of Complications

• Overly rapid correction can lead to cerebral edema and neurological damage
• If correction exceeds planned rate, consider slowing or temporarily stopping fluid administration
• For inadvertent overcorrection, consider therapeutic relowering of serum sodium 2

Addressing Underlying Causes

• Identify and treat the underlying cause:
  • Diabetes insipidus: Consider desmopressin (DDAVP)
  • Excessive sodium intake: Discontinue offending agents
  • Impaired thirst mechanism: Scheduled fluid administration
  • Excessive water losses: Replace ongoing losses

Pitfalls to Avoid

• Do not correct too rapidly: Brain cells adapt to hypernatremia by generating idiogenic osmoles; rapid correction can lead to cerebral edema
• Do not use pure water intravenously: This can cause hemolysis
• Do not rely solely on calculated deficits: Ongoing losses and other factors require frequent reassessment
• Do not ignore potassium: Monitor and correct concurrent electrolyte abnormalities

Follow-up

• Continue monitoring serum sodium until stable
• Transition to oral fluids when possible
• Address preventive measures based on underlying cause
• Educate patient/caregivers about adequate fluid intake if appropriate

Hypernatremia management requires careful attention to correction rates and frequent monitoring to prevent neurological complications while effectively normalizing serum sodium levels.