woman-and-baby

 

Case: Zoe is a 10 day old ex- full term female, born to a G1P0 →1 presenting with feeding difficulties. Per her mother, she is exclusively breastfed and had initially had been doing “ok” but for the last couple days, has been more sleepy than usual and not feeding as well. She also notes that during this time, her eyes have become a bit more yellow.

 

On exam, you note an infant in no distress, but she sleeps comfortably through your exam. Jaundice is appreciated. Vitals are normal, but you note she has lost 12% of her birth weight. Her HEENT is notable for a sunken anterior fontanelle. Her exam is otherwise benign. Concerned for hyperbilirubinemia and dehydration, you order a complete metabolic panel, which, among other abnormalities, is significant for a serum sodium of 165 meq/L.

 

Why is her sodium so high?

Diagnosis: Severe neonatal hypernatremic dehydration

 

Pathophysiology

  • In this case, the most likely etiology is ineffective breastfeeding (also termed lactation failure), which is a rare, but increasing cause of hypernatremic dehydration (Mortiz et al, 2002)
  • In all humans (not just neonates), hypernatremia results from one of two mechanisms: inadequate access to free water and/or an inability to concentrate urine
  • Breastfeeding failure leads to inadequate fluid intake, but is also related to the higher concentration of sodium in breast milk (Morton, 1994)

 

How do patients present? (Moritz et al, 2005)

scaleOver 70% of patients had > 10% weight loss

 

Signs at Presentation

% Of Infants (n=70)

Jaundice 81
Poor PO Intake 61
Decreased Urine Output 36
Fever 20

Table Adapted from Moritz et al, 2005

 

How common is this problem?

  • Neonatal hypernatremic dehydration is rare. A review of admissions to a major children’s hospital found that over 4 years, 1.9% of term and near term infants were admitted for hypernatremic dehydration (Mortiz et al., 2005)
  • Most commonly affects primiparous mothers

 

How should we treat?

  • The goal of treatment is to lower serum sodium in a slow and controlled fashion
  • Conventional teaching states that sodium should not be lowered faster than 0.5mEq/hr and in fact, recent studies suggest that correction faster than 0.5mEq/L/hr is independently associated with poor neurologic outcomes and seizures (Bolat et al, 2013)
  • Specifics (based on protocol detailed in Bolat et al)
    • Emergency Phase
      • Correct shock immediately (within 30 mins) with 10-20 cc/kg 0.9% saline
    • Rehydration Phase
      • Calculated Free Water Deficit
      • Composition of fluid for rehydration is dependent on serum sodium; remember, in patients with high serum concentrations, “normal saline” will be hypotonic (154 meq/L)
      • Serum sodium should be decreased by 0.5meq/L/hr over the first 24-48 hours
      • If a patient is urinating, add 40 meq potassium to fluids

 

What are the neurological outcomes?

  • In the aforementioned study (Bolat et al, 2013), researchers found that presenting serum sodium >160 meq/L was an independent predictor of mortality (OR: 1.9) and correction faster than 0.5 meq/hr was independently associated with an increased risk of seizures (OR: 4.3)
  • At 6 months of age, patients were screened with the Denver Developemental Screening Test II. Serum sodium > 165 meq/L on presentation was associated with worse outcome.

Conclusions

  • Neonatal hypernatremic dehydration is a rare complication of exclusive breastfeeding, primarily seen with primiparous mothers and  can have devastating consequences
  • Clinicians need to be aware of this complication and ensure infants  who are exclusively breastfed are followed closely to ensure adequate breastfeeding and weight gain
  • If hypernatremic dehydration is encountered, it is imperative to 1.) treat shock initially and 2.) ensure that serum sodium is NOT corrected faster than 0.5 meq/hour

Resident Reviewer: Marie Carillo, MD

References

  • Ahmed A et al. “Complications Due to Breastfeeding Associated Hypernatremic Dehydration.” Journal of Clinical Neonatology. 2014;3(3):153-157
  • Bolat F et al. “What Is the Safe Approach for Neonatal Hypernatremic Dehydration?” Pediatric Emergency Care. 2013;29(7):808-813
  • Moritz ML et al. “Breastfeeding-Associated Hypernatremia: Are We Missing the Diagnosis?” Pediatrics. 2005;116(3):e343-e347
  • Moritz ML et al. “Disorder of Water Metabolism in Children: Hyponatremia and Hypernatremia.” Pediatrics in Review. 2002;23(11):371-380
  • Morton J. “The Clinical Usefulness of Breast Milk Sodium in the Assessment of Lactogenesis” Pediatrics. 1994;93(5):802-806