The Purple Book

Hyperkalaemia

Definition

• Normal: 3.5-5.3mmol/L
• Mild hyperkalaemia: 5.4-5.9
• Moderate hyperkalaemia: 6.0–6.4
• Severe hyperkalaemia: ≥ 6.5

Important rates of change:

• sudden (within 1 week) rise in potassium
• >10% increase in serum creatinine or >10% decrease in eGF

Causes

• Excessive intake
• Decreased excretion
• acute or chronic AKI/CKD
• DKA
• drug causes, especially..

Symptoms

• Frank muscle paralysis
• Chest pain, dyspnea, Palpitations
• Nausea or vomiting
• Paresthesias

ECG changes in rough order of appearance:

• Peaked T waves with a shortened QT interval
• prolonged PR and QRS complex
• disappearance of p wave
• widening of QRS eventually progressing to a sine wave before asystole

Management

5.4 – 5.9 mmol/L

• If GFR has not decreased by >10% AND rise in potassium not recent (within 1 week): Review patients medications and consider any changes
• Develop plan for monitoring U&E (liaise with medical staff as needed)
• If GFR has decreased >10% or recent rise in potassium (within 1 week): Review potential causes and repeat U&E within 48h
• If not improving discuss with medical team
• Provide advice re stopping/reducing high potassium foods e.g banana, black chocolate apricots, squash

Potassium 6.0 – 6.4 mmol/L

• Assess for presence of high-risk features:
  • Fall in eGFR (>10ml/min, or >25%)
  • Acute Kidney Injury
  • New eGFR <45ml/min
  • Bicarbonate =< 15mmol/L
  • Any ECG changes (where ECG possible) – peaked T-waves, widened QRS, absent P wave, sine wave
• If high risk features present arrange assessment in hospital
• If no high risk features present – contact patient and assess
• Review medication, consider if medications can be stopped safely
• Repeat U&E within 24-48h
• Provide advice re stopping/reducing high potassium foods e.g banana, black chocolate apricots, squash

Potassium ≥ 6.5

• High risk
• Should attend ED for repeat potassium +/- treatment