What are the signs of hypernatremia?

Signs and Symptoms of Hypernatremia

Hypernatremia (serum sodium >145 mmol/L) presents with various neurological and systemic manifestations that reflect cellular dehydration and brain dysfunction, requiring prompt recognition and appropriate management to prevent serious complications. 1, 2

Clinical Manifestations

Neurological Signs

• Lethargy, headache, and altered mental status are early neurological manifestations 2
• Confusion, delirium, and impaired consciousness with worsening hypernatremia 2
• Ataxia and gait instability as brain cells shrink due to osmotic water shifts 2
• Seizures in severe cases, particularly with rapid development of hypernatremia 2, 3
• Brain herniation and death in extreme cases if left untreated 2, 4

Systemic Signs

• Thirst (if consciousness and thirst mechanism are intact) 5
• Dry mucous membranes and poor skin turgor reflecting overall dehydration 3
• Muscle weakness and cramps 2
• Nausea and vomiting 2
• Fever may be present in severe cases 3

Severity Classification

• Mild hypernatremia: Serum sodium 146-150 mmol/L 2
• Moderate hypernatremia: Serum sodium 151-159 mmol/L 2
• Severe hypernatremia: Serum sodium ≥160 mmol/L 2, 4

Special Populations

Pediatric Patients

• In neonates, hypernatremia is often iatrogenic, resulting from:
  • Incorrect replacement of transepidermal water loss 1
  • Inadequate water intake 1
  • Excessive sodium intake during the transition phase 1
• Symptomatic hypovolemia may accompany hypernatremia in infants 1

Critically Ill Patients

• Impaired consciousness prevents normal thirst-regulated water intake 3
• May present with hemodynamic instability if significant volume depletion exists 3
• Often have multiple contributing factors (inadequate free water, excessive sodium administration) 3

Diagnostic Considerations

Physical Examination Findings

• Assessment of volume status is crucial (hypovolemic, euvolemic, or hypervolemic) 5
• Evaluate for signs of dehydration (dry mucous membranes, decreased skin turgor) 3
• Neurological assessment to determine severity and guide treatment urgency 2

Laboratory Evaluation

• Serum electrolytes, including sodium, potassium, and chloride 1
• Serum and urine osmolality 5
• Urine sodium concentration to help determine etiology 5
• Assessment of acid-base status 1

Complications of Hypernatremia

• Cerebral shrinkage and potential tearing of cerebral vessels leading to intracranial hemorrhage 4
• Permanent neurological damage with rapid development or inappropriate correction 1, 4
• Increased mortality in critically ill patients 3
• Seizures and coma in severe cases 2, 4

Treatment Considerations

• Correction rate should be carefully controlled to avoid cerebral edema 1
• For chronic hypernatremia, reduction rate of 10-15 mmol/L/24h is recommended 1
• Treatment must address both the sodium excess and the underlying cause 5
• Rapid correction may induce cerebral edema, seizures, and neurological injury 1, 4

Common Pitfalls

• Failure to recognize hypernatremia in patients with altered mental status 2
• Overly rapid correction leading to cerebral edema and neurological damage 1, 4
• Not addressing the underlying cause while treating the electrolyte abnormality 5
• Inadequate monitoring during correction of severe hypernatremia 3
• Overlooking hypernatremia in critically ill patients with multiple medical problems 3