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
Pheochromocytoma predominantly secretes which hormone: September 2007 
Select and explain. 
A. Serotonin, B. Epinephrine, C. Nor-epinephrine, D. Dopamine
C: Nor-epinephrine
Answer: C: Nor-epinephrine 
Explanation: 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.