Treating Hypernatremic Dehydration

Abstract

1. Andrew L. Schwaderer, MD 1. Fellow, Pediatric Nephrology 1. George J. Schwartz, MD 1. Professor of Pediatrics Chief, Division of Pediatric Nephrology University of Rochester School of Medicine & Dentistry Rochester, New York In the November 2004 “Index of Suspicion,” Case 1 featured a patient who had hypernatremic dehydration. Dr Scott Hamilton raised the issue of which intravenous solution should be used to treat this condition, given the dangers inherent in lowering the serum sodium level too quickly. Drs Schwaderer and Schwartz have written this commentary to guide clinicians through the complexities of this therapeutic challenge. During most of January, an earlier version of this commentary was printed in the online edition of Pediatrics in Review. This amended version, which was substituted online in late January for the previous commentary, is the text that readers should consult because some corrections were made by the authors. — LFN Hypernatremia, a frequently encountered electrolyte disorder, is defined as a serum sodium level greater than 145 mEq/L (145 mmol/L) and represents a deficit of water in relation to total body sodium. Hypernatremic dehydration may be caused by pure water loss (diabetes insipidus), hypotonic fluid loss (vomiting or diarrhea), or hypertonic sodium gain (hypertonic feeding preparations such as improperly prepared infant formula). (1) Severe hypovolemic hypernatremic dehydration induces brain shrinkage, which can tear the cerebral blood vessels, leading to cerebral hemorrhage, seizures, paralysis, and encephalopathy. (2)(3) Infants who have severe hypernatremia (serum sodium, >160 mEq/L [160 mmol/L]) often present with muscle weakness, a high-pitched cry, insomnia, or lethargy. (1) Younger children tend to have both a higher morbidity and mortality with severe hypernatremia. (2) Breastfeeding hypernatremic dehydration results when a mother-infant feeding interaction is inadequate. In this case, human milk production is limited, and the physiologic decline in human milk sodium concentration does not occur. (4) Forty cases of hypernatremia due to human milk failure have been described in the medical literature. …