Hypernatremia

Definition

Hypernatremia is a serum sodium concentration greater than 145 mEq/L, indicating relative water deficit (too little water relative to sodium).

Causes

• Dehydration, inadequate water intake
• Excessive water loss (diarrhea, vomiting, sweating, diabetes insipidus)
• Hypertonic IV fluids, tube feedings without free water flushes
• Diabetes insipidus
• Osmotic diuresis (hyperglycemia)

Signs and Symptoms

Thirst (most reliable), dry mucous membranes, decreased skin turgor, tachycardia, hypotension, oliguria, lethargy, irritability, seizures, coma. Severe: cerebral shrinkage and hemorrhage.

Nursing Interventions

Replace water slowly. Rapid correction causes cerebral edema. Use hypotonic IV fluids (0.45% NS or D5W) with goal to decrease sodium less than 10 mEq/L per 24 hours. Monitor neuro status, serum Na, and urine output. Daily weights and I&O. For tube feedings, ensure adequate free water flushes.

NCLEX Relevance

Slow correction to avoid cerebral edema. Correlates with dehydration.