What is the standard magnesium dose for torsades de pointes in pediatrics?

• A. 5-10 mg/kg
• B. 25-50 mg/kg
• C. 75-100 mg/kg
• D. 150-200 mg/kg

Answer: (B)

Magnesium helps treat torsades de pointes by stabilizing cardiac membranes and suppressing the abnormal electrical activity (early afterdepolarizations) that occurs with a prolonged QT. In children, the dose is given as a weight-based IV bolus to reach effective levels quickly while keeping safety in mind. The standard bolus dose is 25-50 mg/kg, with a per-dose maximum around 2 grams, typically administered over 10–20 minutes. This range is used because it reliably raises magnesium to therapeutic levels across a wide pediatric size range without causing significant toxicity.

Doses lower than this may be insufficient to terminate or prevent recurrence of torsades, while doses above this range increase the risk of adverse effects such as hypotension, respiratory depression, or loss of reflexes—especially in smaller children or those with renal impairment. If torsades recurs after the bolus, clinicians may repeat dosing or proceed to additional management steps per protocol, often continuing to monitor magnesium levels and clinical response.