Mannitol is given in Cushing syndrome to achieve which effect?

• A. Lower intracranial pressure
• B. Increase blood glucose
• C. Decrease urinary output
• D. Cause vasoconstriction

Answer: (A)

The main idea is lowering intracranial pressure with an osmotic therapy. Mannitol raises the osmolality of the blood, which pulls water out of swollen brain tissue into the bloodstream. That reduces brain edema and lowers intracranial pressure, a critical goal in conditions with cerebral edema like those seen with elevated ICP in Cushing syndrome. It also promotes diuresis to help remove the excess water, so the concept isn’t about decreasing urine output. It doesn’t work by causing vasoconstriction or by raising blood glucose; the desired effect here is ICP reduction.