# Hyponatremia after pediatric surgery: Randomized trial of fluid composition on antidiuretic hormone response

## TL;DR

This study found that giving very low-sodium fluids after surgery can cause low blood sodium in children, especially when antidiuretic hormone levels remain high.

## Contribution

The study identifies that extremely hypotonic fluids during postoperative maintenance increase hyponatremia risk under persistent antidiuretic hormone secretion.

## Key findings

- Hyponatremia occurred in 39% of patients receiving 34 mEq/L sodium solutions.
- Excessive antidiuretic hormone secretion persisted in 90% of patients on postoperative day 3.
- Using Ringer’s solution during the invasive phase reduced hyponatremia risk in hypotonic groups.

## Abstract

We examined the underlying mechanisms of whether hyponatremia could be induced by hypotonic solution administration after the postoperative invasive phase (POIP).

We included patients who had undergone surgery with expected oral feeding resumption after postoperative day (POD) 3. In this open-label, randomized controlled trial, 100 patients were assigned to three groups by sodium concentrations ([Na]) used for maintenance infusions: 136 mEq/L (ISO) (n = 34), 68 mEq/L (HYPO) (n = 33), and 34 mEq/L (exHYPO) (n = 33). Potassium (20 mEq/L) and glucose (60 g/L) were added to each infusion. Ringer’s solution was used in all groups for the first 12 h postoperatively, then switched to a maintenance solution. Blood samples were drawn and evaluated on POD 3.

Hyponatremia frequencies on POD 3 were 3.6, 18, and 39% in the ISO, HYPO, and exHYPO groups, respectively, with a significant difference between the ISO and exHYPO groups. Additionally, 90% of the patients still had excessive antidiuretic hormone (ADH) secretion on POD 3. There were no remarkable adverse events.

The persistence of surgical stress-induced ADH secretion until POD 3 suggested that hyponatremia was induced by exHYPO administration. However, using Ringer’s solution during the POIP might prevent hyponatremia in HYPO patients.

UMIN000029057 (https://www.umin.ac.jp/ctr/index.htm).

01/11/2017

After the postoperative invasive phase, non-osmotic antidiuretic hormone (ADH) secretion due to surgical stress persisted, resulting in an excess ADH state for at least 3 postoperative days (PODs).Administration of extremely hypotonic electrolyte infusions under such circumstances might induce hyponatremia.Adequate extracellular fluid administration during the invasive phase after major pediatric laparoscopic surgery did not cause further increases in ADH secretion or hyponatremia, even for HYPO maintenance fluid.

After the postoperative invasive phase, non-osmotic antidiuretic hormone (ADH) secretion due to surgical stress persisted, resulting in an excess ADH state for at least 3 postoperative days (PODs).

Administration of extremely hypotonic electrolyte infusions under such circumstances might induce hyponatremia.

Adequate extracellular fluid administration during the invasive phase after major pediatric laparoscopic surgery did not cause further increases in ADH secretion or hyponatremia, even for HYPO maintenance fluid.