In a patient with severe pre-eclampsia receiving magnesium sulphate infusion, the first clinical sign of magnesium toxicity to disappear is:

• A Respiratory rate
• B Patellar reflex ✓
• C Urine output
• D Oxygen saturation

Explanation

Loss of deep tendon reflexes (patellar reflex) is the earliest and most reliable clinical sign of magnesium toxicity, occurring at serum levels of approximately 7–10 mEq/L. Respiratory depression occurs at higher levels (~10–13 mEq/L) and cardiac arrest at levels above 15 mEq/L. Monitoring the patellar reflex before each bolus or during infusion is the standard bedside safety check.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.