This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
Shanti has been diagnosed to have brain tumor. You would prefer to give her betamethasone/dexamethasonc over hydrocoisonc as steroids to decrease her cerebral edema because: 
Select and explain. 
A. They do not cause Na+ and water retention, B. They are more potent, C. They can be administered intravenously, D. They inhibit brain tumours
A: They do not cause Na+ and water retention
Answer: A: They do not cause Na+ and water retention 
Explanation: (Ref: KDT 6/e p285) Triamcinolone, betamethasone, dexamethasone and paramethasone are selective glucocoicoids (have zero mineralocoicoid action). These are preferred for cerebral edema because they lack salt and water retaining potential (mineralocoicoid action).