Treatment of Hyponatremia with Seizures, Coma, or Cardiorespiratory Distress
Hyponatraemia — serum sodium below 135 mmol/l — becomes a medical emergency when severe neurological or cardiorespiratory symptoms are present. This protocol covers the first-line approach for that specific, high-acuity presentation.
Clinical Scenario
Hyponatraemia is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. This protocol applies when the biochemical finding of serum sodium <135 mmol/l is accompanied by any of the following severe symptoms:
- Vomiting
- Cardiorespiratory distress
- Abnormal and deep somnolence
- Seizures
- Coma (Glasgow Coma Scale ≤8)
Approach to Treatment
Management centres on prompt intravenous correction of serum sodium with close serial biochemical and clinical monitoring, transitioning to cause-specific treatment once symptoms improve — the full sequence and parameters are in the structured protocol.
Treatment Target
A 5 mmol/l increase in serum sodium concentration within the first hour, with measurable improvement of severe symptoms.
References
- Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice.
- We define 'severely symptomatic' hyponatraemia as any biochemical degree of hyponatraemia in the presence of severe symptoms of hyponatraemia.
- We recommend prompt i.v. infusion of 150 ml 3% hypertonic over 20 min (1D).
- Manage patients with severely symptomatic hyponatraemia in an environment where close biochemical and clinical monitoring can be provided (not graded).
- We suggest repeating therapeutic recommendations 7.1.1.1 and 7.1.1.2 twice or until a target of 5 mmol/l increase in serum sodium concentration is achieved (2D).
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