Hyperkalaemia
Raised serum potassium → cardiac membrane instability
Overview
A raised serum potassium that threatens fatal arrhythmia. Severity and ECG changes drive urgency: cardiac protection with calcium gluconate first, then insulin–dextrose (± salbutamol) to shift potassium intracellularly, then removal.
Recognise
- Often asymptomatic until arrhythmia; muscle weakness, palpitations
- ECG: peaked/tented T waves → widened QRS → loss of P waves → sine wave → VF/asystole
- Causes: AKI/CKD, ACE-i/ARB/spironolactone, rhabdomyolysis, Addison’s, acidosis
Red flags
- ECG changes or K+ >6.5 = emergency → calcium first; arrhythmia/cardiac arrest risk
Differentials & how to tell them apart
Investigations
Urgent U&E (exclude haemolysed sample), ECG immediately, ABG, glucose; identify the cause (drugs, AKI, acidosis).
Management
ECG changes/K+ >6.5: IV calcium gluconate (protect heart) → insulin–dextrose ± salbutamol → remove K+
- 1If ECG changes or K+ >6.5: IV calcium gluconate to stabilise the myocardium FIRST, then insulin (with dextrose) ± nebulised salbutamol to shift potassium.Gate: Calcium gluconate protects the heart but does NOT lower potassium — it must be FOLLOWED by a shifting agent (insulin–dextrose) and then removal
- 2Remove potassium (oral/rectal binders, dialysis if AKI/refractory); stop offending drugs; treat the cause; recheck K+ and glucose.
Key points
Sequence is protect → shift → remove. Watch for rebound and for insulin-induced hypoglycaemia after the shift. Stop ACE-i/ARB/K+-sparing diuretics.
Monitor & prognosis
Continuous ECG, repeat K+ and glucose (post insulin–dextrose), urine output.
Good if treated promptly; otherwise fatal arrhythmia.
Source: UK Renal Association / Resuscitation Council UK hyperkalaemia guideline