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
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