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: Medicine
[{'content': 'Pheochromocytoma predominantly secretes which hormone: September 2007 \nSelect and explain. \nA. Serotonin, B. Epinephrine, C. Nor-epinephrine, D. Dopamine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C: Nor-epinephrine Relative catecholamine levels also differ in pheochromocytomas. Most pheochromocytomas secrete norepinephrine predominantly, whereas secretions from the normal adrenal medulla are composed of roughly 85% epinephrine. Familial pheochromocytomas are an exception because they secrete large amounts of epinephrine. Thus, the clinical manifestations of a familial pheochromocytoma differ from those of a sporadic pheochromocytoma.', 'role': 'assistant'}]