The intravenous (IV) fluid currently recommended for the majority of hospitalised children worldwide should change, a new study says.

The Murdoch Childrens Research Institute and The Royal Children's Hospital study showed that children who receive hypotonic IV fluid, which is routinely administered to maintain hydration, are at higher risk of developing hyponatremia (a low blood sodium level).

The condition can lead to serious side effects including death.

Researchers performed the largest and most diverse study ever of its kind, comparing hypotonic IV fluid with isotonic fluid which contains more sodium (77mmol/L vs 140mmol/L).

The results showed that children receiving the isotonic fluid had a lower risk of their blood sodium levels dropping, without an increase in other adverse effects.

It is possible that the finding could completely change which IV fluid is given to children in hospital all around the world.

Intravenous fluid is one of the most common medical interventions given to hospitalised children, but up until now the composition of the fluid used has been based on poor evidence. Hypotonic IV fluid has been associated with rare but very serious side effects, including death, due to its effect on sodium in the blood. When the sodium level in the body drops quickly, it can lead to brain swelling and death.

The study, which was published in The Lancet, involved 690 children from three months of age up to 18 years old and is the largest inpatient trial performed at The Royal Children's Hospital campus. It involved patients from almost all clinical departments and wards within the hospital.

Lead researcher, Dr Sarah McNab, said the study should have widespread implications and could change the fluid that is given to all hospitalised children worldwide.

“In this study we have demonstrated that by changing the intravenous fluid we routinely use, we can reduce hyponatraemia - an abnormality that sometimes leads to serious side effects.”

“These findings were consistent across hospitalised children, medical and surgical patients.

“Based on these findings, widespread changes to intravenous fluid guidelines should be made,” Dr McNab said.