This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Most sensitive test for diagnosing pheochromocytoma is : 
Select and explain. 
A. MRI, B. 24 hour urinary xma, C. MIBG scan, D. Plasma free metanephrines
D: Plasma free metanephrines
Answer: D: Plasma free metanephrines 
Explanation: Plasma free metaneprines is the most sensitive test.
24 hour urinary VMA is used for screening.
MRI is the IOC for extraadrenal pheochromocytomos.