How to manage hypernatremia in a neonate?

Management of Hypernatremia in Neonates

Correct hypernatremia slowly at a rate of 10-15 mmol/L per 24 hours to prevent cerebral edema, seizures, and permanent neurological injury, after first assessing volume status and replacing plasma volume if symptomatic hypovolemia is present. 1

Initial Assessment and Etiology

Determine the underlying cause by assessing intravascular volume and hydration status before initiating treatment. 1

Hypernatremia (Na >145 mmol/L) in neonates is frequently iatrogenic and results from: 1

• Inadequate water intake - most common in breastfed term neonates with insufficient lactation 2, 3, 4
• Incorrect replacement of transepidermal water loss (TEWL) - particularly in very low birth weight infants (VLBWI) 1
• Excessive sodium intake - often inadvertent during parenteral nutrition 1

Check for signs of hypovolemia: tachycardia, hypotension, decreased skin turgor, sunken fontanelle, and oliguria. 3

Measure urine output and serum electrolytes immediately to guide fluid selection and correction rate. 1, 5

Treatment Algorithm

Step 1: Address Hypovolemia First

If symptomatic hypovolemia is present, restore plasma volume with isotonic saline (0.9% NaCl) at 10-20 mL/kg boluses before attempting sodium correction. 1

This is critical because attempting to correct hypernatremia in a hypovolemic patient can worsen outcomes. 1

Step 2: Calculate Correction Rate

Never correct hypernatremia faster than 10-15 mmol/L per 24 hours. 1

• Rapid correction induces cerebral edema, seizures, and permanent neurological damage 1, 4
• More severe hypernatremia (>160 mmol/L) requires even more cautious correction due to higher risk of treatment complications 2
• A slower correction rate appears safer in severe cases 2

Step 3: Select Appropriate Fluids

Use hypotonic fluids for sodium correction, but administer them slowly and with careful monitoring. 2, 3

For ongoing maintenance after volume resuscitation: 5

• Reduce sodium intake in parenteral nutrition
• Increase free water provision
• Monitor serum sodium every 4-6 hours during active correction 1

In extreme hypernatremia (>200 mmol/L), consider peritoneal dialysis in addition to intravenous fluids to achieve controlled sodium correction. 6

Step 4: Address Underlying Cause

For breastfed neonates with inadequate lactation: 2, 3, 4

• Provide lactation support immediately
• Consider temporary formula supplementation until lactation improves
• Monitor weight loss (should not exceed 10% in term neonates) 5

For VLBWI on parenteral nutrition: 1

• Increase fluid intake to replace TEWL (environmental factors like phototherapy and radiant warmers increase losses) 5
• Reduce sodium content in parenteral nutrition solutions
• Use predominantly acetate-based salts rather than chloride salts 7, 5

Monitoring During Treatment

Monitor the following parameters closely during correction: 1, 5, 3

• Serum sodium every 4-6 hours until stable
• Urine output (target >1 mL/kg/hour) 8, 5
• Daily weights to assess fluid balance 8, 5
• Neurological status (watch for seizures, altered mental status, lethargy) 1, 3, 4
• Signs of cerebral edema during correction 1

Critical Pitfalls to Avoid

Do not correct hypernatremia rapidly - this is the most dangerous error and causes cerebral edema, seizures, and permanent brain damage. 1, 4

Do not use fluid restriction alone - hypernatremia requires active correction with appropriate fluids, not restriction. 4

Do not ignore volume status - always assess and correct hypovolemia before attempting sodium correction. 1

Do not overlook breastfeeding failure - this is the most common cause in term neonates and requires immediate lactation support and possible supplementation. 2, 3, 4

Do not use excessive chloride - in preterm infants on parenteral nutrition, high chloride loads can worsen metabolic acidosis and should be avoided by using acetate-based salts. 7, 5