What is the management for hypernatremia (elevated sodium level)?

Management of Hypernatremia (Sodium 148 mEq/L)

For a sodium level of 148 mEq/L, implement gradual correction with hypotonic fluids at a rate not exceeding 10 mmol/L per 24 hours, while identifying and treating the underlying cause. 1

Initial Assessment

Determine the chronicity and volume status immediately:

• Acute hypernatremia (<24-48 hours) allows faster correction without significant neurological risk 2, 3
• Chronic hypernatremia (>48 hours) requires slow correction to prevent cerebral edema, seizures, and permanent neurological injury 1, 2
• Assess for signs of hypovolemia: orthostatic hypotension, tachycardia, dry mucous membranes, decreased skin turgor 3
• Check urine osmolality and volume to differentiate between water loss vs. sodium excess 2, 4
• Measure urine sodium concentration to guide diagnosis 4

Correction Strategy

Maximum correction rate: 10-15 mmol/L per 24 hours for chronic hypernatremia 1, 2

For your patient with sodium 148 mEq/L:

• Target reduction of 10 mmol/L over 24 hours (bringing sodium to ~138 mEq/L) 1
• If acute onset (<24 hours), faster correction is permissible 2, 3
• Never exceed 10 mmol/L reduction in 24 hours if chronicity is uncertain 1, 2

Fluid Replacement

Use hypotonic fluids for correction:

• 0.45% NaCl (half-normal saline) for moderate hypernatremia with some volume depletion 3
• 0.18% NaCl or D5W for more aggressive free water replacement if severe or with adequate volume status 3
• Avoid isotonic (0.9%) saline as this will worsen hypernatremia 3

Calculate water deficit:

• Water deficit (L) = 0.5 × body weight (kg) × [(current Na/140) - 1] 3
• Replace deficit over 24-48 hours depending on chronicity 3, 4
• Add ongoing losses and insensible losses (typically 500-1000 mL/day) 4

Monitoring Protocol

Check serum sodium every 4-6 hours during active correction:

• Monitor for overly rapid correction (>10 mmol/L/24h) which risks cerebral edema 1, 2
• Track daily weights and strict intake/output 1
• Adjust fluid rate based on sodium response 4
• Watch for neurological symptoms: confusion, seizures, altered consciousness 2, 3

Identify and Treat Underlying Cause

Common etiologies to address:

• Dehydration from inadequate water intake: most common in elderly or impaired thirst mechanism 3, 4
• Excessive water losses: diarrhea, vomiting, diuretics, osmotic diuresis 2, 4
• Diabetes insipidus: if urine osmolality <300 mOsm/kg with polyuria, consider desmopressin 2, 4
• Iatrogenic causes: hypertonic saline, sodium bicarbonate, tube feeds without adequate free water 2, 4

Special Considerations

For diabetes insipidus specifically:

• Administer desmopressin (DDAVP) 1-2 mcg subcutaneously or 10-20 mcg intranasally 2
• Continue hypotonic fluid replacement 2

If severe symptoms or sodium >160 mEq/L:

• Consider ICU monitoring 3
• More aggressive correction may be warranted but still respect maximum rates 3

Critical Pitfalls to Avoid

• Too rapid correction of chronic hypernatremia causes cerebral edema, seizures, and permanent brain injury 1, 2
• Using isotonic saline will worsen hypernatremia in patients with free water deficit 3
• Inadequate monitoring during correction leads to overcorrection complications 1, 4
• Starting renal replacement therapy without adjusting for sodium can cause precipitous drops 2