This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Surgery
Which of the following is best for diagnosis of pheochromocytoma? 
Select and explain. 
A. 24-hour urinary Vaniyll Mandelic acid, B. 24-hour urinary Fractionated Metanephrine, C. 24-hour Urinary Hydroxy indole acetic acid, D. 24-hour Urinary Hydroxy tryptamine
B: 24-hour urinary Fractionated Metanephrine
Answer: B: 24-hour urinary Fractionated Metanephrine 
Explanation: Pheochromocytoma Most sensitive screening test for pheochromocytoma- Urinary catecholamines and Vanillyl mandelic acid (VMA)level. Best test for diagnosis of pheochromocytoma- 24 hours plasma fractionated Metanephrine > 24 hours urinary plasma fractionated Metanephrine 24 hours urinary hydroxy indole acetic acid is performed for carcinoid tumors