Electrolyte emergencies
also: hyperkalaemia · calcium gluconate · hyponatraemia · hypomagnesaemia · SIADH
Overview
The drug treatments for the dangerous electrolyte disturbances — hyperkalaemia (the classic ECG emergency), calcium, magnesium and sodium correction.
Mechanism
Targeted correction: calcium gluconate stabilises the cardiac membrane (does not lower K⁺); insulin+dextrose and salbutamol shift K⁺ intracellularly; the cause is then treated. Calcium/magnesium/sodium are replaced at controlled rates to avoid harm (e.g. central pontine myelinolysis).
Indications
- Hyperkalaemia
- Hypocalcaemia
- Hypomagnesaemia
- Hyponatraemia / SIADH
- Hypokalaemia
The agents
Calcium gluconate PROTECTS the heart (membrane); insulin/dextrose ± salbutamol SHIFT K⁺; then remove K⁺ (diuretics/dialysis/binders).
Acute symptomatic (tetany, ↑QT) → IV 10% calcium gluconate; chronic → vitamin D analogue + calcium.
Correct Mg FIRST in refractory hypokalaemia/hypocalcaemia.
Correct Na SLOWLY (<10 mmol/L/24h) — rapid rise → central pontine myelinolysis.
Adverse effects
From over-rapid sodium correction — "low to high, the pons will die".
Monitor glucose after treating hyperkalaemia.
Common misconception — it protects the heart only.
Cautions & contraindications
Central pontine myelinolysis.
Interactions
- Hypokalaemia/hypomagnesaemia potentiate digoxin toxicity
Monitoring & kinetics
Continuous ECG (K⁺/Ca²⁺), repeat U&E, glucose after insulin/dextrose, Na rate of change
Mostly IV in the acute setting. Treat the underlying cause alongside.
Source: Resus Council UK — Hyperkalaemia · BNF — Fluids & electrolytes