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Bolus fluid therapy and sodium homeostasis in paediatric gastroenteritis


  • Stephen B Freedman,

    Corresponding author
    • Sections of Emergency Medicine and Gastroenterology, Department of Paediatrics, Children's Hospital and Alberta Children's Hospital Research Institute, University of Calgary, Alberta
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  • Denis F Geary

    1. Nephrology, The Hospital for Sick Children, Ontario, Canada
    2. Child Health Evaluative Sciences, Hospital for Sick Children Research Institute, The Hospital for Sick Children, Ontario, Canada
    3. Department of Paediatrics, Faculty of Medicine, University of Toronto, Ontario, Canada
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  • Declaration of conflict of interest: The authors have no conflicts of interest to declare. The first draft of the manuscript was written by Stephen Freedman. No honorarium, grant or other form of payment was given to anyone to produce the manuscript.
  • Funding

    Funding for the collection of data performed in this study was provided by a grant from The Physicians' Services Incorporated Foundation (principal investigator: S. Freedman).

    The clinical trial which served as the basis for data collection for this study was registered at (number, NCT00392145).

  • Presentations

    This study was presented at the 2012 Pediatric Academic Societies' Annual Meeting; Boston, MA, 28 April 2012, and the Canadian Pediatric Society's 89th Annual Conference, London, ON, 7 June 2012.

Correspondence: Dr Stephen B Freedman, Section of Emergency Medicine, Alberta Children's Hospital, 2888 Shaganappi Trail NW, Calgary, AB, Canada T3B 6A8. Fax: 416-813-5043; email:



The study aims to assess the risk of developing hyponatraemia when large-volume bolus fluid rehydration therapy is administered.


We conducted a prospective randomised study in a tertiary-care centre emergency department. Participants included children with gastroenteritis and dehydration requiring intravenous rehydration. They were randomised to receive 60 mL/kg (large) or 20 mL/kg (standard) 0.9% saline bolus followed by maintenance 0.9% saline for 3 h. Biochemical tests were performed at baseline and 4 h. The primary outcome measure was the development of hyponatraemia at 4 h. Secondary outcome measures were (i) change in sodium relative to baseline value; (ii) magnitude of decrease among those who experienced a decrease; (iii) risk of hypernatraemia; (iv) correlations between urine parameters and hyponatraemia; and (v) fluid overload.


Eighty-four of 224 (38%) participants were hyponatraemic at baseline. At 4 h, 22% (48/217) had a dysnatraemia, and similar numbers of children were hyponatraemic in both groups: large (23% (26/112)) versus standard (21% (22/105)) (P = 0.69). Among initially hyponatraemic children, 63% (30/48) who received large-volume rehydration and 44% (15/34) of those administered standard rehydration were isonatraemic at 4 h (P = 0.10). Overall, children who received 60 mL/kg experienced a larger mean increase (1.6 ± 2.4 mEq/L vs. 0.9 ± 2.2 mEq/L; P = 0.04) and were less likely to experience a sodium decrease of ≥2 mEq/L (8/112 vs. 17/105; P = 0.04) than those administered 20 mL/kg.


Large-volume bolus rehydration therapy with 0.9% saline is safe. It does not promote the development of hyponatraemia over the short term, but hastens the resolution of baseline hyponatraemia.