How to manage hypernatremia?

Management of Hypernatremia (Sodium 147 mEq/L)

For a sodium level of 147 mEq/L, correct the hypernatremia slowly with hypotonic fluids at a rate not exceeding 8-10 mEq/L per 24 hours, while simultaneously identifying and treating the underlying cause. 1

Initial Assessment

Your patient has mild hypernatremia (normal range: 135-145 mEq/L). The first critical step is determining the mechanism:

• Assess volume status clinically: Look for signs of dehydration (dry mucous membranes, decreased skin turgor, orthostatic hypotension) versus volume overload (edema, jugular venous distention) 2, 3
• Check urine osmolality and sodium: This distinguishes between renal and extrarenal water losses 4, 3
  • Urine osmolality >600-800 mOsm/kg suggests extrarenal losses (insensible losses, GI losses)
  • Urine osmolality <300 mOsm/kg suggests diabetes insipidus
• Review medications and recent fluid administration: Many ICU patients develop iatrogenic hypernatremia from inadequate free water provision 3

Treatment Strategy Based on Volume Status

For Hypovolemic Hypernatremia (Most Common)

• Administer hypotonic fluids (0.45% saline or D5W) to replace free water deficit 2, 4
• Calculate free water deficit: 0.6 × body weight (kg) × [(current Na/140) - 1] 2
• Replace half the deficit over first 24 hours, remainder over next 24-48 hours 4

For Hypervolemic Hypernatremia

• Use loop diuretics (furosemide) to promote free water excretion and reduce volume overload 1
• Monitor cardiac output during diuresis, especially in heart failure patients 1
• In cirrhotic patients, avoid rapid sodium changes and consider free water restriction alongside diuretics 1

For Euvolemic Hypernatremia (Diabetes Insipidus)

• Administer desmopressin (DDAVP) if central diabetes insipidus is confirmed 4
• Provide free water replacement orally if patient is conscious, or D5W intravenously 4

Critical Correction Rate Guidelines

The most important principle: Do not correct chronic hypernatremia (>48 hours duration) faster than 8-10 mEq/L per 24 hours. 1, 4

• For acute hypernatremia (<24 hours), more rapid correction is safer 4
• Overly rapid correction of chronic hypernatremia causes cerebral edema due to osmotic shifts 1, 4
• Monitor serum sodium every 2-4 hours during active correction 1

Special Populations

Patients with Liver Disease or Cirrhosis

• Correct even more cautiously to avoid cerebral edema 1
• Monitor for hepatorenal syndrome during diuretic therapy 1
• A sodium of 150 mEq/L in cirrhosis may indicate worsening hemodynamic status 5

Critically Ill Patients

• Many ICU patients have impaired consciousness and cannot regulate water balance through thirst 3
• The intensivist must carefully manage sodium and water balance rather than relying on patient-driven intake 3
• Hypernatremia is an independent risk factor for increased mortality in critical illness 3

Patients with Cerebral Edema

• In some protocols for managing cerebral edema, sodium levels of 150-155 mmol/L are deliberately targeted 5
• This is a specific exception where mild hypernatremia is therapeutic 5

Common Pitfalls to Avoid

• Failing to distinguish acute from chronic hypernatremia: Chronic cases require slower correction 4
• Using isotonic fluids in patients with renal concentrating defects: These patients need hypotonic replacement 5
• Inadequate monitoring during correction: Check sodium levels every 2-4 hours initially 1
• Not addressing the underlying cause: Simply correcting sodium without treating the etiology leads to recurrence 2, 3

Monitoring During Treatment

• Serum sodium every 2-4 hours during active correction 1
• Watch for neurological changes (confusion, seizures) suggesting cerebral edema from overly rapid correction 4
• Monitor urine output and osmolality to assess response 4, 3
• Reassess volume status frequently 2, 3