A patient with eclampsia is receiving magnesium sulfate infusion. She develops loss of deep tendon reflexes. Her respiratory rate is 10/min and urine output is 25 mL/hour. Which of the following is the MOST appropriate immediate action?
- A Increase the magnesium infusion rate to control impending seizures
- B Give furosemide to improve urine output
- C Administer calcium gluconate 1 g IV and stop magnesium infusion ✓
- D Switch to phenytoin for seizure prophylaxis
Correct answer: C. Administer calcium gluconate 1 g IV and stop magnesium infusion
Explanation
Loss of deep tendon reflexes is the earliest sign of magnesium toxicity, occurring at serum levels of approximately 7–10 mEq/L. Respiratory arrest occurs at higher levels. The antidote for magnesium toxicity is calcium gluconate 1 g IV, which should be given immediately while stopping the magnesium infusion. Monitoring for reflexes is crucial because they serve as a bedside guide to safe magnesium dosing.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.