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Common hyperkalemia exam questions for medical finals, OSCEs and MRCP PACES


Question 1.

List the three stages of hyperkalaemia

  • Mild: 5.5-6.0 mM
  • Moderate: 6.1-6.9 mM
  • Severe: ≥7.0 mM


Question 2.

List the four broad causes of hyperkalaemia

  • Excess intake
  • Release from intracellular fluid (ICF)
  • Inadequate excretion
  • Pseudohyperkalaemia: laboratory artefact typically caused by haemolysis during venepuncture


Question 3.

List the classic changes occurring in hyperkalaemia and the order in which the usually occur

  • 1. Flattened P waves
  • 2. Tall tented T waves
  • 3. Wide QRS becoming sinusoidal

List the other possible ECG changes in hyperkalaemia

  • Flattened P waves
  • Prolonged PR interval (first degree heart block)
  • Prolonged QRS interval
  • Shortened QT interval
  • ST segment depression
  • Tall tented T waves
  • Sinusoidal QRST
  • Bradycardia
  • Pulsed monomorphic ventricular tachycardia (VT)
  • Cardiac arrest rhythms are not listed here as they should only be seen on a defibrillator or cardiac monitor, not an ECG!


Question 4.

List the four main strategies in treating hyperkalaemia

  • Myocardial protection
  • Drive potassium into ICF
  • Potassium elimination
  • Identify and treat the cause

List three drugs you would give immediately

  • Calcium chloride or gluconate 10 ml of 10% by slow IV injection
  • Salbutamol 5 mg nebuliser
  • Insulin-dextrose infusion:  10 units of actrapid in 50 ml of 50% dextrose over 30 minutes


Question 5.

When would you consider CRRT in hyperkalaemia?

  • If serum potassium concentration >6.5 mM and refractory to medical management