How to treat a patient with severe hypernatremia (elevated sodium level)?

Treatment of Hypernatremia (Sodium Level of 156)

The treatment of hypernatremia with a sodium level of 156 should focus on administering hypotonic fluids, preferably 5% dextrose in water, with careful calculation of the water deficit and a correction rate not exceeding 8-10 mmol/L per day to prevent neurological complications. 1, 2

Initial Assessment and Causes

• Hypernatremia (serum sodium >145 mmol/L) represents an imbalance in water balance, usually resulting from increased free water loss compared to sodium excretion 1
• Common causes include:
  • Inadequate water intake (most common in hospitalized patients) 3
  • Excessive water loss (diabetes insipidus, diarrhea, vomiting) 4
  • Rarely, excessive sodium intake 1

Treatment Approach

Fluid Selection and Administration

• Avoid salt-containing solutions, especially 0.9% NaCl, as they increase renal osmotic load and can worsen hypernatremia 5
• Use water with dextrose (5% dextrose) as the primary fluid for free water replacement 5, 1
• Calculate the initial rate of fluid administration based on physiological demand:
  • Children: First 10 kg: 100 ml/kg/24h; 10-20 kg: 50 ml/kg/24h; remaining 50 kg: 20 ml/kg/24h 5
  • Adults: 25-30 ml/kg/24h 5

Correction Rate Guidelines

• For chronic hypernatremia (>48 hours), limit correction to 8-10 mmol/L per day 1, 3
• For acute hypernatremia (<24 hours), more rapid correction may be considered, but still requires close monitoring 1
• The induced change in serum osmolality should not exceed 3 mOsm/kg/h 5

Monitoring During Treatment

• Monitor serum sodium levels frequently (every 2-4 hours initially, then every 4-6 hours) 2
• Assess hemodynamic status, fluid input/output, and clinical examination to judge successful progress 5
• For patients with renal or cardiac compromise, monitor serum osmolality and frequently assess cardiac, renal, and mental status to avoid iatrogenic fluid overload 5

Special Considerations

For Patients with Nephrogenic Diabetes Insipidus

• Low salt (<6 g/day) and protein diet (<1 g/kg/day) may be beneficial 5
• Consider discontinuing prostaglandin synthesis inhibitors in adults 5
• Thiazide diuretics may be considered based on patient preference 5

For Patients with Cerebral Edema

• In some clinical protocols, sodium levels of 150-155 mmol/L may be deliberately targeted for management of cerebral edema 6
• This requires careful neurological monitoring and specialist consultation

Calculation of Water Deficit

• Water deficit can be calculated using the formula:
  • Water deficit = Total body water × [(Current Na⁺/140) - 1] 2
  • Total body water is approximately 60% of body weight in kg for adult men, 50% for adult women, and 70% for children 2

Common Pitfalls to Avoid

• Administering isotonic or hypertonic fluids, which can worsen hypernatremia 5
• Correcting chronic hypernatremia too rapidly, which can lead to cerebral edema 1, 7
• Inadequate monitoring of serum electrolytes during correction 2, 3
• Failing to identify and treat the underlying cause of hypernatremia 4, 2

Specific Treatment Algorithm

1. Determine chronicity: Acute (<48 hours) or chronic (>48 hours) 1
2. Calculate water deficit using the formula above 2
3. Select appropriate fluid: 5% dextrose in water for most cases 5, 1
4. Determine correction rate:
   • Chronic: 8-10 mmol/L/day maximum 1, 3
   • Acute: Can be more aggressive but still requires monitoring 1
5. Monitor serum sodium every 2-4 hours initially 2
6. Adjust fluid rate based on sodium correction achieved 2
7. Identify and treat underlying cause (e.g., diabetes insipidus may require desmopressin) 4, 1

Remember that hypernatremia is associated with high morbidity and mortality, especially in older patients, and requires prompt but careful management 3.