What is the treatment for hypernatremia?

Treatment of Hypernatremia

Critical Assessment and Initial Management

For hypernatremia, the primary treatment is restoration of plasma tonicity through free water replacement, with the rate of correction determined by whether the condition is acute (<24-48 hours) or chronic (>48 hours). 1, 2

Determine Acuity and Correction Rate

• Acute hypernatremia (<24-48 hours): Rapid correction improves prognosis by preventing cellular dehydration effects, and hemodialysis is an effective option for severe cases 1, 2
• Chronic hypernatremia (>48 hours): Slow correction rate of no more than 0.4 mmol/L/hour or 8-10 mmol/L per 24 hours is mandatory to prevent osmotic demyelination syndrome 1, 2

Identify Underlying Etiology

The diagnostic approach requires assessing volume status and urine studies to guide treatment 3:

• Hypervolemic hypernatremia: Excessive sodium intake (hypertonic saline, NaHCO3 solutions acutely; primary hyperaldosteronism chronically) - treat with diuretics to promote renal sodium excretion 1, 4
• Euvolemic hypernatremia: Diabetes insipidus (central or nephrogenic) - requires desmopressin for central DI or addressing underlying cause (discontinue lithium, correct hypokalemia) for nephrogenic DI 1, 2
• Hypovolemic hypernatremia: Renal or extrarenal water losses - requires hypotonic fluid replacement 1

Fluid Replacement Strategy

Calculate Water Deficit

Water deficit = 0.5 × body weight (kg) × [(current Na/140) - 1] - this guides the total volume of free water needed 3

Select Appropriate Replacement Fluid

• Hypotonic solutions (D5W or 0.45% NaCl) are the primary replacement fluids for hypernatremia 5, 2
• For severe hypernatremia requiring IV fluids, hypotonic fluid replacement is necessary 5
• Replace ongoing water losses and insensible losses (typically 500-1000 mL/day) in addition to the calculated deficit 3

Monitor Correction Rate Closely

• Check serum sodium every 2-4 hours initially during active correction to ensure the rate does not exceed safe limits 2
• Adjust infusion rates based on serial sodium measurements to maintain the target correction rate 3

Special Considerations

Critically Ill Patients

• Hypernatremia is an independent risk factor for increased mortality in ICU patients 4
• Many critically ill patients have impaired consciousness and cannot regulate water balance through thirst, requiring meticulous physician management of sodium and water balance 4

Diabetes Insipidus

• Central diabetes insipidus: Administer desmopressin (Minirin) as definitive therapy 2
• Nephrogenic diabetes insipidus: Address underlying causes (discontinue lithium, correct electrolyte abnormalities like hypokalemia) 1

Renal Replacement Therapy

• When initiating dialysis in patients with chronic hypernatremia, carefully adjust dialysate sodium concentration to avoid rapid drops in serum sodium 2
• For acute severe hypernatremia, hemodialysis can rapidly normalize sodium levels when clinically indicated 2

Common Pitfalls to Avoid

• Overly rapid correction of chronic hypernatremia leading to cerebral edema and osmotic demyelination syndrome - always limit correction to 8-10 mmol/L per 24 hours for chronic cases 1, 2
• Inadequate monitoring during correction - frequent sodium checks are essential 2
• Failing to replace ongoing losses - only correcting the initial deficit without accounting for continued water losses 3
• Ignoring the underlying cause - hypernatremia will recur if the primary disorder (e.g., diabetes insipidus, impaired thirst mechanism) is not addressed 5, 3