Magnesium sulfate therapeutic range is which of the following?

• A. 4-7 mEq/L
• B. 2-3 mEq/L
• C. 8-10 mEq/L
• D. 1-2 mEq/L

Answer: (A)

Magnesium sulfate is given to prevent seizures in preeclampsia, and the safe, effective serum level for this anticonvulsant effect is 4 to 7 mEq/L. Staying in this range provides seizure protection while minimizing toxicity. If the level drops below this, seizure prevention may be inadequate. If it rises above this range, toxicity becomes a concern, with signs like loss of deep tendon reflexes, respiratory depression, decreased urine output, and potential cardiovascular instability. That’s why clinicians monitor the magnesium level regularly (often every few hours) and assess reflexes, breathing, and urine output, ready to administer calcium gluconate as an antidote if toxicity develops. The other ranges are either too low to provide protection or too high and risk harm.