# Comparison of Serum Sodium Levels Following Intravenous Administration of Isotonic and Hypotonic Solutions in Young Children: A Randomized Controlled Trial

## TL;DR

This study compared how isotonic and hypotonic IV fluids affect blood sodium levels in young children and found isotonic fluids better maintain sodium without complications.

## Contribution

The study provides new evidence on the safety and efficacy of isotonic IV fluids in maintaining serum sodium in young children.

## Key findings

- Isotonic fluids caused a greater increase in serum sodium at 24 hours compared to hypotonic fluids.
- No significant cases of hyponatremia or hypernatremia occurred in either group.
- Both groups had similar rates of hyperchloremic metabolic acidosis and no complications.

## Abstract

Objectives: This study evaluated changes in serum sodium (S Na) 24 h after the administration of isotonic versus hypotonic intravenous fluids (IVFs) and the incidences of dysnatremia and hyperchloremic metabolic acidosis. Methods: This double-blind, randomized controlled trial involved children aged 3 months to 5 years who were admitted to a general ward between November 2020 and September 2022 and required IVF. We randomly assigned patients (1:1) to receive either an isotonic solution (D50.9%NaCl) or hypotonic solution (D50.45%NaCl). Serum electrolyte and venous blood gas levels were obtained at the time of IVF administration and 24 and 48 h after IVF administration. During this study, all participants were monitored for vital signs, body weight, fluid intake and output, and clinical symptoms of dysnatremia. Results: Totals of 69 and 68 patients received isotonic and hypotonic solutions, respectively. The mean age was 1.95 ± 1.25 years in the isotonic group and 1.91 ± 1.32 years in the hypotonic group. The initial degrees of dehydration and biochemical indicators were not different. The change in serum sodium level at 24 h was 2.97 (2.32–3.62) mmol/L in the isotonic group and 2.19 (1.54–2.84) mmol/L in the hypotonic group. In both groups, no significant hyponatremia nor hypernatremia occurred. The incidence of hyperchloremic metabolic acidosis was not different between the groups. Neither group showed any complications. Conclusions: Isotonic fluids may be a preferred option for IVFs in pediatric patients under 5 years of age with medical conditions on a general ward, especially within 24 h, due to their potential to better maintain serum sodium levels without increasing the risk of fluid overload or electrolyte complication.