The purpose of this guideline is to provide clinical guidance for all staff involved in the care and management
of severe hyponatraemia in paediatric patients at the Queensland Children’s Hospital (QCH).
Mild to moderate hyponatraemia is very common in paediatric practice and can usually be reduced by avoiding
intravenous (IV) hypotonic electrolyte solutions. This guideline will deal with the potentially life-threatening
situation of severe hyponatraemia (serum sodium less than 120 mmol/L) where there is risk of central
demyelination as a consequence of rapid correction of sodium.
Hyponatraemia is the most common electrolyte abnormality encountered in children. Hyponatraemia results
from an excess of water relative to sodium in the extracellular fluid compartment. Severe hyponatraemia is
defined as a serum sodium level less than 120 mmol/L or as a rapid fall in serum sodium levels. It is associated
with increased morbidity and mortality and can lead to a wide spectrum of clinical symptoms.
It is most common in children with pre-existing morbidities and may have delayed presentation as part of critical
illness. The management of hyponatraemia can commence within any area of the hospital under care of a
variety of specialist medical teams.
Investigations
Routine pathology should include:
• Serum sodium
• Plasma osmolarity
• Urine osmolarity
• Urine sodium
Management
If there are no neurological manifestations of hyponatraemia, active correction with Sodium Chloride 3%
solution is not required and potentially harmful.
Consult the QCH Endocrinology team for all cases of symptomatic hyponatraemia.
ALERT
Rapid correction of serum sodium is associated with osmotic demyelination syndrome
Rise in serum sodium should not exceed 10mmol/L in the first 24 hours and 18mmol/L
in the first 48 hours.
Refer to Appendix 3 for further details
Consider insertion of an arterial line or large bore venous line to allow for frequent blood sampling during
sodium correction.
Management of confirmed severe hyponatraemia (less than 120 mmol/L) with presence of
symptoms:
1. Treat shock (if present) with appropriate fluid resuscitation using Sodium Chloride 0.9%. Pause and
reassess. Fluid resuscitation may cause a rise in serum sodium as diuresis occurs. Monitor urine output.
2. Administer 1.5 to 2.5 mmol/kg (3 to 5 mL/kg) of Sodium Chloride 3% over 30 minutes, preferably via a
central line, using Dose Error Reduction Software (DERS). Do not delay treatment in a symptomatic
patient if central access is not available.
3. Check serum sodium concentration immediately following the Sodium Chloride 3% infusion. Aim to
correct the sodium by 6 mmol/L.
4. If still symptomatic and serum sodium remains < 125 mmol/L, repeat administration of 1.5 to 2.5
mmol/kg (3 to 5 mL/kg) of Sodium Chloride 3% over 30 minutes. 
Consultation
Key stakeholders who reviewed this version:
• Pharmacist Senior – Critical Care
• Pharmacist Lead Critical Care
• SMO PICU
• Safety and Quality PICU
• SMO Endocrine