Which electrolyte disturbance causes a prolonged QT interval and torsades de pointes when severe?
Answer and explanation
Correct answer: A. Hypokalaemia or hypomagnesaemia
- Step 1: Low potassium and magnesium delay ventricular repolarisation.
- Step 2: Intravenous magnesium treats torsades de pointes.
Answer
Hypokalaemia or hypomagnesaemia.
Why not the others: 'Hypernatraemia' does not typically prolong the QT; 'Hyperphosphataemia' does not typically prolong the QT; 'Hypercalcaemia' shortens the QT interval.
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