This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pregnancy induced Hypeension, Subject name: Gynaecology & Obstetrics
Magnesium sulphate toxicity include all EXCEPT 
Select and explain. 
A. Loss of Patellar reflex, B. Oliguria, C. Respiratory depression, D. Cardiac arrest
B: Oliguria
Answer: B: Oliguria 
Explanation: MgSo4 acts by inhibition of neuromuscular transmission. NOTE: we monitor urine output while patient is on MgSO4, not because it is a sign of MgSO4 toxicity, but because oliguria is secondary to PIH (glomerular endotheliosis) and decreased urine output would decrease MgSO4 clearance and increase risk of toxicity. Serum Mg2+ levels(meq/l) Clinical effects 4-7 Normal therapeutic level 8 - 10 Patellar reflex disappear 10-15 Respiratory depression 12-15 Respiratory paralysis 25 - 30 Cardiac arrest