Acute in-hospital hyponatremia in children: an observational study

Introduction

To develop hyponatremia (plasma sodium concentration (P_Na) < 136 mM), there must be a source of electrolyte free water (EFW) and actions of antidiuretic hormone (ADH) to prevent its excretion. A low P_Na is the most common electrolyte disorder in hospitalized children and it makes them more prone to neurological damage.

Objectives

To establish the incidence of and to identify risk factors for the development of hospital-acquired hyponatremia in a tertiary care hospital.

Methods

We included all children (n = 432) who had two or more P_Na-measurements in the Emergency Department in a 3-month period and in hospital over the first 48 hours.

Results

The incidence of hyponatremia was 22.5% of whom 14.4% were hyponatremic on presentation and 9.3% developed hyponatremia in hospital (five patients fell in both groups). ADH was likely elevated due to disease (7.9%; e.g. bronchiolitis), symptoms (47%; e.g. nausea) and treatment (45.1%; e.g. surgery). Eighty-three percent of the EFW responsible for the falls in P_Na was administered as either hypotonic intravenous (66%) or oral fluids (34%) and was excessive in 53% of the cases. Those who did not seem to receive excessive EFW had an occult source of water, hyperglycemia (16%), mannitol (8%) and/or excreted hypertonic urine (62%).

Conclusions

The most important factor for hospital-acquired hyponatremia is the administration of hypotonic fluids. Hospital-acquired hyponatremia is iatrogenic and therefore preventable. It unnecessarily puts children at risk of neurological damage. The practice of IV-fluid therapy should be re-evaluated.