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
Which of the following is the earliest sign of magnesium toxicity in a patient with eclampsia on treatment with magnesium sulphate: 
Select and explain. 
A. Loss of deep tendon reflexes, B. Respiratory depression, C. Cardiac arrest, D. Decreased urine output
A: Loss of deep tendon reflexes
Answer: A: Loss of deep tendon reflexes 
Explanation: -During Magnesium toxicity, the first reflex to be lost is patellar reflex (loss of knee jerk) -While giving MgSO4 things should be monitored are as follows; Respiratory rate should be at least more than 12 Output should be more than 100 ml / 4hrs Knee jerks should be present 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